class Concurrent::Tuple
A fixed size array with volatile (synchronized, thread safe) getters/setters. Mixes in Ruby's `Enumerable` module for enhanced search, sort, and traversal.
@example
tuple = Concurrent::Tuple.new(16) tuple.set(0, :foo) #=> :foo | volatile write tuple.get(0) #=> :foo | volatile read tuple.compare_and_set(0, :foo, :bar) #=> true | strong CAS tuple.cas(0, :foo, :baz) #=> false | strong CAS tuple.get(0) #=> :bar | volatile read
@see en.wikipedia.org/wiki/Tuple Tuple
entry at Wikipedia @see www.erlang.org/doc/reference_manual/data_types.html#id70396 Erlang Tuple
@see ruby-doc.org/core-2.2.2/Enumerable.html Enumerable
Constants
- Tuple
@!visibility private
Attributes
The (fixed) size of the tuple.
Public Class Methods
Create a new tuple of the given size.
@param [Integer] size the number of elements in the tuple
# File lib/concurrent/tuple.rb, line 33 def initialize(size) @size = size @tuple = tuple = Tuple.new(size) i = 0 while i < size tuple[i] = Concurrent::AtomicReference.new i += 1 end end
Public Instance Methods
Set
the value at the given index to the new value if and only if the current value matches the given old value.
@param [Integer] i the index for the element to set @param [Object] old_value the value to compare against the current value @param [Object] new_value the value to set at the given index
@return [Boolean] true if the value at the given element was set else false
# File lib/concurrent/tuple.rb, line 73 def compare_and_set(i, old_value, new_value) return false if i >= @size || i < 0 @tuple[i].compare_and_set(old_value, new_value) end
Calls the given block once for each element in self, passing that element as a parameter.
@yieldparam [Object] ref the `Concurrent::AtomicReference` object at the current index
# File lib/concurrent/tuple.rb, line 82 def each @tuple.each {|ref| yield ref.get} end
Get the value of the element at the given index.
@param [Integer] i the index from which to retrieve the value @return [Object] the value at the given index or nil if the index is out of bounds
# File lib/concurrent/tuple.rb, line 47 def get(i) return nil if i >= @size || i < 0 @tuple[i].get end
Set
the element at the given index to the given value
@param [Integer] i the index for the element to set @param [Object] value the value to set at the given index
@return [Object] the new value of the element at the given index or nil if the index is out of bounds
# File lib/concurrent/tuple.rb, line 59 def set(i, value) return nil if i >= @size || i < 0 @tuple[i].set(value) end


---
layout: post
title: Speed up your ActiveRecord queries with Model.select
date: '2015-01-27T13:47:00.000-08:00'
author: Mark J. Lehman
tags:
- ruby
modified_time: '2015-08-21T10:06:46.796-07:00'
blogger_id: tag:blogger.com,1999:blog-4459370175540830177.post-5413339325325059366
blogger_orig_url: http://spaghettirefactory.blogspot.com/2015/01/speed-up-your-activerecord-queries-with.html
---
Say you want to display a list of all your users' names and link to their show pages. Instead of running User.all
, instantiating every field of every user, there's a better way. Since you only need the name and id or slug (for the link), better to run:
@users = User.select(:name, :email)
@users.first.accessed_fields
. This is primarily helpful in development mode so you know which fields you have access to. However, I couldn't get this to work locally, might need to be using master branch of Rails. Read more here: https://github.com/rails/rails/commit/be9b680


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Contact information of investigator(s):
br>
Model grid type:
Polar Stereographic
Horizontal grid spacing (or equivalent node spacing for spectral models):
Model vertical coordinate and number of vertical levels:
sigma, 20 levels
Model dynnamics:
nonhydrostatic, compressible
Lateral boundary relaxation method and number of points in buffer zone:
Dynamical diffusion over 9 grid points
Number of soil layers for which soil temperature is computed:
Number of soil layers for which soil water content is computed:
Number of surface vegetation types:
Formulation for boundary-layer fluxes (e.g., local K-theory based upon gradient Richardson number):
Representation of explicit precipitation (e.g., rain and ice physics):
Prognostic variables for explicit precipitation (e.g., cloud water; rain water; number of ice species):
Formulation for convective parameterization (e.g., Kuo-type):
Reference(s) containing model description:
Reference(s) describing land-surface parameterization:
Reference(s) describing convective parameterization:
Reference(s) describing boundary-layer parameterization:
Reference(s) describing explicit precipitation paramerization:


| P - 'Pro' - Total Entries: 10 Trophies: 5 |
|
Run 1.. |
Run 2.. |
Run 3.. |
Run 4.. |
Total |
| 1T |
STR |
95 |
Buck Merritt
|
2008 Honda S2000 |
|
57.063 |
63.649 |
64.275 |
63.978+1 |
47.362 |
|
|
|
|
|
|
63.962 |
64.743 |
64.930 |
|
[-]0.454 |
| 2T |
STS |
59 |
Ahmad Huang
|
1988 Honda CRX |
|
59.120 |
58.455 |
64.905 |
63.507 |
47.816 |
|
|
|
|
|
|
63.770 |
62.964+3 |
62.577 |
|
+0.454 |
| 3T |
STS |
194 |
Monroe Drew
|
1993 Toyota MR2 |
|
61.078+DNF |
58.131+1 |
62.050 |
62.764+2 |
49.187 |
|
|
|
|
|
|
62.468+1 |
62.488 |
61.973+4 |
|
+1.371 |
| 4T |
AS |
196 |
Manual Latham
|
2002 Chevrolet Corvette Z06 |
|
58.721+1 |
65.069 |
66.791 |
67.139+3 |
49.730 |
|
|
|
|
|
|
67.211 |
66.514 |
67.586+1 |
|
+0.543 |
| 5 |
ES |
555 |
Jerrell Urbina
|
1999 Mazda Miata Sport |
|
60.728+1 |
76.679+4 |
69.109+1 |
67.055 |
49.806 |
|
|
|
|
|
|
66.888 |
66.249 |
66.456 |
|
+0.076 |
| 6 |
FS |
53 |
Samual Gandy
|
2017 Chevrolet Camaro |
|
58.762+2 |
64.369 |
66.694 |
66.770+2 |
50.460 |
|
|
|
|
|
|
67.257 |
66.183+2 |
66.031+1 |
|
+0.654 |
| 7 |
FP |
147 |
Ahmed Eason
|
1973 Datsun 240Z |
|
59.323 |
58.287 |
|
|
50.884 |
|
|
|
|
|
|
|
|
|
|
+0.424 |
| 8 |
STS |
94 |
Aldo Burkholder
|
1993 Toyota MR2 |
|
59.110+3 |
64.948+1 |
63.354 |
64.426+DNF |
51.381 |
|
|
|
|
|
|
63.727+1 |
64.185 |
62.813 |
|
+0.497 |
| 9 |
AS |
96 |
Diego Camarillo
|
2002 Chevrolet Corvette Z06 |
|
71.936 |
69.152 |
71.804+3 |
81.873+2 |
56.635 |
|
|
|
|
|
|
75.027+DNF |
70.285+1 |
|
|
+5.254 |
| 10T |
CS |
78 |
Adolph Wenzel
|
2016 Mazda MX-5 |
|
|
|
|
|
DNS |
|
|
|
|
|
|
|
|
|
|
|
| BS - 'B Street' - Total Entries: 5 Trophies: 2 |
|
Run 1.. |
Run 2.. |
Run 3.. |
Run 4.. |
Total |
| 1T |
|
4 |
Franklyn Shull
|
2006 Honda S2000 |
|
70.542+DNF |
67.442 |
66.960 |
67.378+1 |
65.776 |
|
|
|
|
|
|
65.776 |
66.706 |
66.175 |
|
[-]1.127 |
| 2T |
|
93 |
Hunter Schell
|
2002 Chevrolet Corvette |
|
68.923 |
68.143 |
67.091 |
69.770 |
66.903 |
|
|
|
|
|
|
68.617 |
67.911 |
66.903 |
|
+1.127 |
| 3 |
|
83 |
Quintin Sheets
|
2007 Pontiac Solstice |
|
70.190 |
69.337 |
68.133 |
69.922 |
68.133 |
|
|
|
|
|
|
69.042 |
70.008 |
69.653+2 |
|
+1.230 |
| 4 |
|
814 |
Mason Pomeroy
|
2007 Mazda Mx-5 |
|
68.571+DNF |
68.757+1 |
68.288 |
70.580+1 |
68.288 |
|
|
|
|
|
|
68.847+1 |
69.138 |
70.273 |
|
+0.155 |
| 5 |
|
94 |
Patricia Loveless
|
2006 Honda S2000 |
|
72.921 |
73.624 |
72.353 |
73.912 |
72.206 |
|
|
|
|
|
|
73.893 |
72.206 |
72.297 |
|
+3.918 |
| DS - 'D Street' - Total Entries: 5 Trophies: 2 |
|
Run 1.. |
Run 2.. |
Run 3.. |
Run 4.. |
Total |
| 1T |
|
655 |
Margarito Lyle
|
2014 Scion FR-S |
|
69.038 |
67.386 |
67.712 |
68.073 |
66.734 |
|
|
|
|
|
|
67.050 |
67.347 |
66.734 |
|
[-]1.055 |
| 2T |
|
156 |
Donnell Prescott
|
2013 Scion FRS |
|
68.545 |
67.789 |
67.956 |
81.829 |
67.789 |
|
|
|
|
|
|
87.383+DNF |
|
|
|
+1.055 |
| 3 |
|
75 |
Andrea Denning
|
2014 Scion FRS |
|
71.133+ |
68.889 |
69.171 |
68.499+2 |
68.889 |
|
|
|
|
|
|
68.289+2 |
69.311 |
69.310 |
|
+1.100 |
| 4 |
|
56 |
Sal Mabe
|
2015 Subaru BRZ |
|
72.655+1 |
69.453 |
68.956 |
71.506 |
68.956 |
|
|
|
|
|
|
72.042+DNF |
70.802 |
72.178 |
|
+0.067 |
| 5 |
|
175 |
Coy Ripley
|
2014 Scion FR-S |
|
70.773 |
69.906+1 |
70.532+1 |
74.371+1 |
70.443 |
|
|
|
|
|
|
71.253 |
70.719 |
70.443 |
|
+1.487 |
| GS - 'G Street' - Total Entries: 3 Trophies: 1 |
|
Run 1.. |
Run 2.. |
Run 3.. |
Run 4.. |
Total |
| 1T |
|
41 |
Paris Ledford
|
2014 Ford Focus ST |
|
66.617 |
64.866 |
65.208 |
65.814 |
64.866 |
|
|
|
|
|
|
65.593 |
65.433 |
66.392 |
|
[-]0.319 |
| 2 |
|
141 |
Bennett Layton
|
2014 Ford Focus ST |
|
65.846+1 |
64.297+1 |
64.661+1 |
68.430 |
65.185 |
|
|
|
|
|
|
66.861 |
65.185 |
71.258 |
|
+0.319 |
| 3 |
|
29 |
Brain Messenger
|
2016 Volkswagen GTI |
|
75.923 |
73.466 |
70.657 |
73.713 |
70.657 |
|
|
|
|
|
|
72.804 |
70.990 |
77.027 |
|
+5.472 |
| STS - 'Street Touring S' - Total Entries: 7 Trophies: 3 |
|
Run 1.. |
Run 2.. |
Run 3.. |
Run 4.. |
Total |
| 1T |
|
174 |
Gerry Getz
|
1991 Honda Civic |
|
58.863+1 |
58.510 |
65.205 |
64.529 |
58.510 |
|
|
|
|
|
|
64.296 |
63.724+5 |
65.024+1 |
|
[-]0.075 |
| 2T |
|
171 |
Bret Ferris
|
1988 Honda CRX |
|
60.209+DNF |
58.585 |
68.134 |
66.910 |
58.585 |
|
|
|
|
|
|
66.143 |
64.656 |
64.936 |
|
+0.075 |
| 3T |
|
72 |
Quincy Fitzsimmons
|
1989 Honda Civic SI |
|
63.522 |
60.375 |
68.212 |
67.768 |
60.375 |
|
|
|
|
|
|
67.516+1 |
68.604+3 |
68.842+1 |
|
+1.790 |
| 4 |
|
172 |
Vern Gilliland
|
1989 Honda Civic Si |
|
58.481+1 |
65.256+DNF |
66.453 |
66.764+1 |
60.481 |
|
|
|
|
|
|
66.279 |
65.945+2 |
65.503 |
|
+0.106 |
| 5 |
|
117 |
Lucius Eagle
|
1988 Honda CRX |
|
61.686 |
67.468 |
72.635 |
71.171+DNF |
61.686 |
|
|
|
|
|
|
|
|
|
|
+1.205 |
| 6 |
|
74 |
Frances Champagne
|
1991 Honda Civic SI |
|
63.326+1 |
67.838 |
67.461 |
66.883+1 |
65.326 |
|
|
|
|
|
|
67.174+1 |
68.024+2 |
|
|
+3.640 |
| 7 |
|
18 |
Stevie Vaughan
|
1991 Mazda Miata |
|
65.863+1 |
84.646 |
77.978 |
74.505 |
67.863 |
|
|
|
|
|
|
82.967+1 |
76.506+1 |
76.033 |
|
+2.537 |
| STR - 'Street Touring R' - Total Entries: 6 Trophies: 2 |
|
Run 1.. |
Run 2.. |
Run 3.. |
Run 4.. |
Total |
| 1T |
|
2 |
Monte Gillespie
|
2016 Mazda MX5 |
|
59.003 |
66.064 |
66.680 |
67.160 |
59.003 |
|
|
|
|
|
|
67.654 |
68.642+DNF |
68.417+1 |
|
[-]0.311 |
| 2T |
|
96 |
Dewayne Beaulieu
|
2006 Honda S2000 |
|
59.314 |
64.472 |
76.226+1 |
65.902 |
59.314 |
|
|
|
|
|
|
64.875+4 |
66.535+1 |
68.223+DNF |
|
+0.311 |
| 3 |
|
91 |
Alvaro Muncy
|
2001 Honda S2000 |
|
59.576 |
64.836 |
75.128+DNF |
67.584 |
59.576 |
|
|
|
|
|
|
77.751+DNF |
67.809 |
67.693 |
|
+0.262 |
| 4 |
|
196 |
Darius Abernathy
|
2006 Honda s2000 |
|
63.558 |
59.902 |
67.050 |
66.599+1 |
59.902 |
|
|
|
|
|
|
69.022+DNF |
67.286+2 |
67.140+3 |
|
+0.326 |
| 5 |
|
197 |
Fritz Navarrete
|
2005 Honda S2000 |
|
62.234 |
67.126 |
67.895 |
68.684 |
62.234 |
|
|
|
|
|
|
69.934 |
68.930 |
68.055 |
|
+2.332 |
| 6 |
|
8 |
Hassan Bradford
|
2007 Mazda MX-5 Miata |
|
62.037+1 |
69.050 |
68.835 |
69.393 |
64.037 |
|
|
|
|
|
|
70.218 |
69.580 |
69.835+1 |
|
+1.803 |
| N - 'Novice' - Total Entries: 9 Trophies: 3 |
|
Run 1.. |
Run 2.. |
Run 3.. |
Run 4.. |
Total |
| 1T |
STX |
272 |
Alec Rooney
|
1993 BMW 325is |
|
63.438 |
71.867 |
70.051 |
71.249 |
52.146 |
|
|
|
|
|
|
70.391 |
69.680 |
76.787 |
|
[-]5.316 |
| 2T |
FS |
808 |
Mel Velez
|
1998 Audi A4 2.8 Quattro |
|
76.237 |
73.870 |
74.198 |
71.471 |
57.462 |
|
|
|
|
|
|
71.959+1 |
70.865+1 |
74.398+DNF |
|
+5.316 |
| 3T |
GS |
193 |
Shelby Berlin
|
2017 Ford Focus ST |
|
81.741 |
77.525 |
75.311+DNF |
79.386 |
58.570 |
|
|
|
|
|
|
76.873 |
94.890+1 |
73.859 |
|
+1.108 |
| 4 |
GS |
93 |
Ty Gladney
|
2017 Ford Focus ST |
|
81.726 |
78.631+DNF |
75.074 |
78.355 |
59.533 |
|
|
|
|
|
|
75.693 |
75.091 |
75.535 |
|
+0.963 |
| 5 |
STX |
304 |
Hans Luce
|
2012 Honda Civic Si |
|
72.561 |
92.173 |
81.633 |
80.292 |
59.645 |
|
|
|
|
|
|
82.276 |
81.622 |
78.848+2 |
|
+0.112 |
| 6 |
GS |
29 |
Lane Morton
|
2016 Volkswagen GTI |
|
91.042 |
82.201 |
80.905 |
81.744 |
61.210 |
|
|
|
|
|
|
78.678 |
77.188 |
|
|
+1.565 |
| 7 |
CAM-T |
302 |
Mitch Strunk
|
1993 Ford Mustang LX |
|
73.728+1 |
77.354 |
77.074 |
81.516+1 |
61.869 |
|
|
|
|
|
|
78.760+DNF |
78.739 |
77.574+1 |
|
+0.659 |
| 8 |
HS |
68 |
Blaine Hyde
|
1999 Honda Accord LX |
|
96.540 |
91.689 |
85.328 |
87.909 |
66.434 |
|
|
|
|
|
|
84.522 |
84.997+1 |
85.821 |
|
+4.565 |
| 9 |
FP |
318 |
Maximo Hutton
|
1995 BMW 318ti |
|
|
|
|
|
DNS |
|
|
|
|
|
|
|
|
|
|
|
| T - 'Tire Limited' - Total Entries: 9 Trophies: 3 |
|
Run 1.. |
Run 2.. |
Run 3.. |
Run 4.. |
Total |
| 1T |
DSP |
25 |
Valentine Orta
|
2002 BMW 330Ci |
|
62.887 |
69.220 |
86.215 |
70.271 |
51.627 |
|
|
|
|
|
|
68.820 |
|
|
|
[-]1.512 |
| 2T |
CSP |
117 |
Rod Bolton
|
1999 Mazda Miata |
|
63.375 |
70.198 |
74.794 |
71.999 |
53.139 |
|
|
|
|
|
|
73.499 |
73.005 |
|
|
+1.512 |
| 3T |
DSP |
266 |
Mohamed Yamamoto
|
1997 BMW 328is |
|
64.813 |
70.453 |
69.123 |
69.227 |
53.208 |
|
|
|
|
|
|
69.766 |
68.680 |
68.815 |
|
+0.069 |
| 4 |
CSP |
159 |
Mikel Zaragoza
|
1994 Mazda Miata |
|
62.865+1 |
67.651 |
69.120 |
69.059+1 |
54.389 |
|
|
|
|
|
|
68.668 |
68.967 |
67.782 |
|
+1.181 |
| 5 |
SM |
10 |
Daren Bean
|
2009 Subaru WRX STI |
|
64.293+DNF |
69.198 |
70.494 |
69.748 |
58.090 |
|
|
|
|
|
|
71.586 |
69.200 |
70.120 |
|
+3.701 |
| 6 |
SMF |
18 |
Eldon Saucedo
|
2003 Toyota Avalon |
|
|
|
|
|
DNS |
|
|
|
|
|
|
|
|
|
|
|
| 7 |
DP |
193 |
Isiah Fusco
|
2006 Mazda MX-5 |
|
|
|
|
|
DNS |
|
|
|
|
|
|
|
|
|
|
|
| 8 |
SMF |
81 |
Efrain Leung
|
Honda crx |
|
|
|
|
|
DNS |
|
|
|
|
|
|
|
|
|
|
|
| 9 |
FP |
465 |
Danilo Holly
|
2003 Acura CL |
|
|
|
|
|
DNS |
|
|
|
|
|
|
|
|
|
|
|
| OC - 'Open Combined' - Total Entries: 13 Trophies: 4 |
|
Run 1.. |
Run 2.. |
Run 3.. |
Run 4.. |
Total |
| 1T |
STX |
25 |
Dee Mathews
|
2013 Subaru BRZ |
|
59.793 |
59.570 |
59.617+1 |
|
48.966 |
|
|
|
|
|
|
|
|
|
|
[-]4.556 |
| 2T |
AS |
441 |
Antoine Schulz
|
2004 Chevrolet Corvette Z06 |
|
72.097+DNF |
68.110+1 |
65.573+2 |
67.048 |
53.522 |
|
|
|
|
|
|
66.417 |
66.101+1 |
65.351 |
|
+4.556 |
| 3T |
ES |
24 |
Rusty Atchison
|
1999 Mazda Miata |
|
71.187 |
69.336 |
68.040 |
69.712+1 |
54.023 |
|
|
|
|
|
|
69.049+1 |
67.535+3 |
68.177+1 |
|
+0.501 |
| 4T |
ES |
5 |
Alphonso Duvall
|
1990 Mazda miata |
|
72.874 |
71.564 |
70.639+1 |
72.074 |
55.183 |
|
|
|
|
|
|
69.501 |
70.046 |
70.581+1 |
|
+1.160 |
| 5 |
HS |
53 |
Beau Dehart
|
2015 Volkswagen Golf TDI |
|
74.323 |
71.729 |
71.150 |
71.631 |
55.329 |
|
|
|
|
|
|
70.269+3 |
70.394 |
70.939 |
|
+0.146 |
| 6 |
HS |
2 |
Chet Tillery
|
1999 Saturn SC2 |
|
74.153 |
71.890 |
71.300 |
73.085 |
56.041 |
|
|
|
|
|
|
81.270 |
72.299 |
73.923 |
|
+0.712 |
| 7 |
CS |
13 |
Hollis Ireland
|
2013 Mazda MX-5 |
|
72.678 |
72.003 |
71.618 |
71.242 |
56.890 |
|
|
|
|
|
|
71.524 |
70.235 |
70.528 |
|
+0.849 |
| 8 |
AS |
44 |
Garret Daly
|
2008 Honda S2000 CR |
|
74.467 |
70.014 |
70.003 |
90.768+4 |
57.332 |
|
|
|
|
|
|
73.498 |
71.185 |
71.532 |
|
+0.442 |
| 9 |
CS |
20 |
Antony Rowan
|
2009 Mazda MX-5 |
|
72.915 |
73.936 |
72.414 |
75.093 |
58.655 |
|
|
|
|
|
|
82.867 |
74.805 |
74.832 |
|
+1.323 |
| 10 |
ESP |
72 |
Billie Patel
|
1972 Pontiac Firebird |
|
78.112 |
76.318 |
75.202 |
76.288 |
62.841 |
|
|
|
|
|
|
79.785+DNF |
75.079 |
97.529+2 |
|
+4.186 |
| 11 |
SM |
77 |
Brady Houser
|
Nissan 240sx |
|
83.030+1 |
81.515+2 |
79.846 |
80.647+2 |
68.197 |
|
|
|
|
|
|
79.207 |
79.882+1 |
79.880 |
|
+5.356 |
| 12 |
SM |
7 |
Jarrod Gilliam
|
1992 Nissan 240sx |
|
87.363 |
87.015+1 |
82.666 |
85.480 |
71.133 |
|
|
|
|
|
|
84.017+2 |
83.548 |
82.617 |
|
+2.936 |
| 13 |
STX |
68 |
Octavio Henke
|
2015 Subaru WRX |
|
|
|
|
|
DNS |
|
|
|
|
|
|
|
|
|
|
|


Protocols
The following protocols are available globally.
-
The
TimeIntervalLiterals
protocol is used to extendIntegerLiteralType
andFloatLiteralType
to allow for human-readable time notations such as:let sixtySeconds = 60.seconds let twoAndAHalfMinutes = 2.5.minutes let oneWeek = 7.days let anotherWeek = 1.week
Default implementations of the
See moreminutes
,hours
,days
, andweeks
properties are supplied; implementors of theTimeIntervalLiterals
protocol only need to supply an implementation forseconds
.Declaration
Swift
public protocol TimeIntervalLiterals


The Startup Scholarship was born from the wish of some of the best and most engaged students in engineering and management in Portugal to build a new approach for Startups to find talent while at the same time providing an innovative experience and gateway into entrepreneurship for top University students around the world. A summer of intense work, learning and networking, powered by the hard work of a world-class team.


Handling concurrent INSERT with SQLAlchemy
August 17, 2015
In some cases, you may want to have a unique column other than a primary key id.
E.g: email, passport number, national id, vat number, ...
If you have some unique constraints on a table then you may hit some race condition problem in some edge cases. In this post, we will only cover this case base on Postgres, but I assume that the behavior is similar with other RDBMS: Mysql, Oracle, ...
To clarify the context, race condition problem doesn't apply to unique constraint for a column with a sequence for value like a SERIAL (also known as autoincrement ID). The reason is because sequences are non-transactional. You can easily test it by opening 2 psql
and play with sequences. In other words, nexval(sequence)
will never give you the same value, no matter of the transaction and the transaction isolation doesn't apply to it.
To illustrate our problem, we have a model called Link
. This model is used to stored an URL and we don't want any duplicate of URLs in the table so we made this column unique.
from sqlalchemy.ext.declarative import declared_attr, as_declarative
from sqlalchemy import Unicode, Column, Integer
@as_declarative
class Base(object):
@declared_attr
def __tablename__(cls):
return cls.__name__.lower()
id = Column(Integer, primary_key=True)
engine = create_engine('postgresql://test@/test')
DBSession = scoped_session(sessionmaker(bind=engine))
Base.metadata.bind = engine
class Link(Base):
url = Column('url', Unicode, index=True, unique=True, nullable=False)
The link
table is composed of 2 columns:
- an
id
column which is an integer primary key with autoincrement - an
url
column with an unique constraint.
We want to be able to insert new link, but if we try to insert an existing URL then we want to retrieve the existing link of object.
This operation is commonly referred as get or create
and it's a commonly used in Django.
If we don't care about race condition then a first version of the code may look like this:
def get_link_by_url(url):
return DBSession.query(Link).filter(Link.url == url).first()
def get_or_create_link(url):
# 1. Looking for an existing Link object for these url value
link = self.get_link_by_url(url)
if link:
# 2. A Link object exist and we return it
return link
# 3. A Link object doesn't exist so we create an instance
link = Link(url=url)
DBSession.add(link)
# 4. We insert the link object in the table inside this transaction
DBSession.flush()
return link
This code assumes that you have a transaction block created before calling the function get_or_create_link
. In the case of a web framework, often a transaction start and end with the request.
The code above have a problem because it doesn't handle the case
when a Link object has been inserted in the DB
between the time we look into the DB if it exists (step 2) and we create the record (step 4). It will be bad luck, but it happens! To write the code solving this problem, we need to understand how the SQL queries behave.
Let's imagine that we have 2 transactions called T1
and T2
and the operations happens in the following order.
_ T1 ___ T2 _
|
|
BEGIN; x
|
|
DOING STUFF... x
|
|
SELECT * FROM link x
WHERE url = 'http://google.com' |
=> (0 rows) |
|
INSERT INTO link (url) x BEGIN;
VALUES ('http://google.com'); |
=> 1 row inserted |
x DOING STUFF...
|
|
x SELECT * FROM link
| WHERE url = 'http://google.com'
| => (0 rows)
|
x INSERT INTO link (url)
| VALUES ('http://google.com');
| => waiting
|
|
DOING OTHER STUFF... x ... still waiting ...
|
|
COMMIT; x Bam! Integrity Error!
|
|
x ROLLBACK;
|
|
BEGIN; x
|
SELECT * FROM link x
WHERE url = 'http://yahoo.com' |
=> (0 rows) |
|
INSERT INTO link (url) x BEGIN;
VALUES ('http://yahoo.com'); |
=> 1 inserted |
X SELECT * FROM link
| WHERE url = 'http://yahoo.com'
| => (0 rows)
|
x INSERT INTO link (url)
| VALUES ('http://yahoo.com');
| => waiting
|
|
DOING OTHER STUFF... x ... still waiting ...
|
|
ROLLBACK; x => 1 row inserted
|
V
The example above tries to illustrate the race condition between 2 transactions. You can have differents type of concurrency problem base on type of query UPDATE, DELETE, or SELECT FOR UPDATE but the only way to get a conflict during INSERT is if you have a uniqueness constraint on a table. If two concurrent transactions try to insert rows having the same key value, then the second one will block until the first one finishes. If the first transaction commits, the second one must abort because of the uniqueness constraint; but if the first one aborts the second one can proceed.
To handle the race condition in this INSERT case we want the following SQL behavior:
_ T1 ___ T2 _
|
|
BEGIN; x
|
|
DOING STUFF... x
|
|
SELECT * FROM link x
WHERE url = 'http://google.com' |
=> (0 rows) |
|
|
SAVEPOINT sp; x
|
|
INSERT INTO link (url) x BEGIN;
VALUES ('http://google.com'); |
=> 1 row inserted |
x DOING STUFF...
|
|
RELEASE sp; x SELECT * FROM link
| WHERE url = 'http://google.com'
| => (0 rows)
|
|
x SAVEPOINT sp;
|
|
x INSERT INTO link (url)
| VALUES ('http://google.com');
| => waiting
|
|
DOING OTHER STUFF... x ... still waiting ...
|
|
COMMIT; x Bam! Integrity Error!
|
|
x ROLLBACK sp;
|
|
x SELECT * FROM link
| WHERE url = 'http://google.com'
| => (1 rows)
|
|
x DOING OTHER STUFF;
|
|
x COMMIT;
|
V
In the example above, the race condition got handled and the code can continue as expected without having to rollback all the transaction!
This workflow can be translated into Python and SQLAlchemy:
def get_or_create_link(url):
# 1. Looking for an existing Link object for these url value
link = self.get_link_by_url(url)
if link:
# 2. A Link object exist and we return it
return link
# 3. A Link object doesn't exist so we create an instance
link = Link(url=url)
# 4. We create a savepoint in case of race condition
DBSession.begin_nested()
try:
DBSession.add(link)
# 5. We try to insert and release the savepoint
DBSession.commit()
except IntegrityError, e:
# 6. The insert fail do to a concurrent transaction
DBSession.rollback()
# 7. We get the Link which exist now
link = get_link_by_url(url) # 7)
return link
This code has been written taking in consideration that the model has only one unique constraint. If you understand it then it will be easy for you to write your own version to handle your specific use case.
Some other people wrote about the similar topic like in this post. The post tries to provide a generic version of a get_or_create
function. I personally don't encourage this approach because of the difficulty in dealing with concurrency, the get/create pattern is not something a generic approach can eliminate; decisions will have to be made in how the SELECT or INSERT is to solve the problem is approached (see Mike Bayer comment).
It worth to mention that there is the useful SQLAlchemy's UniqueObject recipe, this recipe use the session to keep track of the unique key which helps in some context.
I hope this post will help you to understand a bit more race condition even if it only discuss the simple case of INSERT with a unique constraint. With concurrency, different problem may require different understanding on how the database works: Locking, transaction isolation, etc


-
OneTimeSecret
So for those who use OnetimeSecret all the time, you can add this little function to your .bashrc (or similar) So then you don’t have to openh a browser to share your secret! 1 2 3 4 5 onetimesecret() { if [ $# -eq 0 ]; then echo "No secret...
-
C.H.I.P, flic and openhab
So I finally received my C.H.I.P, and over the break I purchased myself some flic bluetooth buttons with the plan of making some nice push buttons around the home to control openhab. This idea mostly came from usablity/speed of use of openhab. Having the dashboard in the middle of the...
-
Openhab
Since the ninjablock company has run out of money, and is not supporting the ninjablock anymore, and its cloud service is pretty unreliable (at the best of times) I decided to merge all my homeautomation items with Openhab. At the time I adopted this, it was the only major, multi-vendor...
-
Mini DLNA and bubbleUPnP
So ages ago I found bubbleUPnP (also an andoid app). I’d put this in the category of cheap plex server. I say this because the main reason I wanted to use it was for its on-the-fly transcoding to play media to the chromecast. The android app is also really nice,...
-
Upgrading SD on the Raspberry Pi
I’ve been running my Raspberry Pi (V2) for almost a year and a half on a 16gb SD card, but because I run owncloud on the pi, I’ve been slowly running out of space. I know I can just add a usb drive or have owncloud store the data on...
-
building phonegap app for Android and iOS
So I had the pleasure of figuring out how to successfully build and publish a phonegap app, both to the Play store and Apple store. It was bad enough that I have no experience with phonegap/Cordova (or anything iOS development related), but the previous developer had left no documentation. That...
-
Counter Strike and Pebble
Hey all, it’s been a while! I’ve been busy. Combining my enthusiasm to CS and the usefulness of a pebble watch to create you CSontheGO Pretty cool huh? Being able to keep up to date with CS matches from your watch. I decided to do this because I: wanted to...
-
C.H.I.P
So I was too late to the hype of Pi Zero, the $5 Raspberry pi, and have not been able to get my hands on one since the launch. Everywhere has been sold out everytime I check :( I can’t remember how I stumble upon them, but I found an...


CSS concept clinic - Box Model
What is the difference between margin, border, and padding?
17th January 2016
CSS is a very important partner of HTML. When HTML does all the content and structuring, CSS adds all the colors to your website by letting you do all the styling and formatting. Today we are going to explore more on one of the important concepts in CSS - Box Model.
First and foremost, all HTML elements can actually be considered as boxes. In CSS, box model is basically a box that frames every HTML element and is consisting of Margins, Borders, Padding and Content (from outermost to innermost)
This image from w3schools shows a clear illustration of the box model:
Having looked at the box model as a whole, let's look into the components one by one.
Content
This is where the main content located in the entire box model. Content includes text and imagesPadding
This is the transparent spacing between the content and the border. Adding padding makes the box model looks less packed.Border
This is a line wrapping around the padding and the content. It gives you a sense of "box"Margin
This is the transparent spacing outside the border. It is between the border and the next HTML element near it.With all the differences between Padding, Border and Margin illustrated above, there is one common point. For all 3 of them, they can all be broken down into top, right, bottom and left segments. When you are defining the attributes of them you always want to specify which segment you are editing e.g. margin-left: 1px;.


XOR
问题描述 :
XOR is a kind of bit operator, we define that as follow: for two binary base number A and B, let C=A XOR B, then for each bit of C, we can get its value by check the digit of corresponding position in A and B. And for each digit, 1 XOR 1 = 0, 1 XOR 0 = 1, 0 XOR 1 = 1, 0 XOR 0 = 0. And we simply write this operator as ^, like 3 ^ 1 = 2,4 ^ 3 = 7. XOR is an amazing operator and this is a question about XOR. We can choose several numbers and do XOR operatorion to them one by one, then we get another number. For example, if we choose 2,3 and 4, we can get 2^3^4=5. Now, you are given N numbers, and you can choose some of them(even a single number) to do XOR on them, and you can get many different numbers. Now I want you tell me which number is the K-th smallest number among them.
输入:
First line of the input is a single integer T(T<=30), indicates there are T test cases.
For each test case, the first line is an integer N(1<=N<=10000), the number of numbers below. The second line contains N integers (each number is between 1 and 10^18). The third line is a number Q(1<=Q<=10000), the number of queries. The fourth line contains Q numbers(each number is between 1 and 10^18) K1,K2,……KQ.
For each test case, the first line is an integer N(1<=N<=10000), the number of numbers below. The second line contains N integers (each number is between 1 and 10^18). The third line is a number Q(1<=Q<=10000), the number of queries. The fourth line contains Q numbers(each number is between 1 and 10^18) K1,K2,……KQ.
输出:
First line of the input is a single integer T(T<=30), indicates there are T test cases.
For each test case, the first line is an integer N(1<=N<=10000), the number of numbers below. The second line contains N integers (each number is between 1 and 10^18). The third line is a number Q(1<=Q<=10000), the number of queries. The fourth line contains Q numbers(each number is between 1 and 10^18) K1,K2,……KQ.
For each test case, the first line is an integer N(1<=N<=10000), the number of numbers below. The second line contains N integers (each number is between 1 and 10^18). The third line is a number Q(1<=Q<=10000), the number of queries. The fourth line contains Q numbers(each number is between 1 and 10^18) K1,K2,……KQ.
样例输入:
2 2 1 2 4 1 2 3 4 3 1 2 3 5 1 2 3 4 5
样例输出:
Case #1: 1 2 3 -1 Case #2: 0 1 2 3 -1HintIf you choose a single number, the result you get is the number you choose. Using long long instead of int because of the result may exceed 2^31-1.
题目 ：http://acm.hdu.edu.cn/showproblem.php?pid=3949
#include<iostream> #include<cstdio> #include<cstring> #include<map> #include<algorithm> #include<cmath> #include<queue> #include<stack> using namespace std; #define M 10010 #define inf 1LL<<60 #define ll long long #define eps 1e-7 #define bas 9 #define mod<PHONE_NUMBER>LL ll a[M]; ll bit[61]; int n; void gauss() { int row = 0, col = 60, k; while( col >= 0 && row < n ){ k = row; while( k < n && (a[k]&bit[col]) == 0 ) ++k; if( k == n ){ --col; } else{ swap( a[row], a[k] ); for( int i = 0; i < n; ++i ) if( i-row ){ if( a[i]&bit[col] ) a[i] ^= a[row]; } --col, ++row; } } sort( a, a+n ); n = unique( a, a+n ) - a; } ll cal( int x ) { int i = 0; if( a[0] == 0 ){ if( x == 1 ) return 0; ++i; --x; } ll ans = 0; while( x && i < n ){ if(x&1) ans ^= a[i]; x >>= 1; ++i; } if( x ) return -1; return ans; } int main() { //freopen( "input.txt", "r", stdin ); //freopen( "output.txt", "w", stdout ); bit[0] = 1; for( int i = 1; i < 61; ++i ) bit[i] = bit[i-1]<<1; int T, q, t = 0, x; scanf( "%d", &T ); while( T-- ){ scanf( "%d", &n ); for( int i = 0; i < n; ++i ) scanf( "%I64d", a+i ); gauss(); printf( "Case #%d:\n", ++t ); scanf( "%d", &q ); while( q-- ){ scanf( "%d", &x ); cout<<cal(x)<<endl; } } }
版权声明：本文为博主原创文章，未经博主允许不得转载。
参考：http://blog.csdn.net/freezuoguan/article/details/8607587
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这杯子用着喝水一定有股话梅味。
依稀记得许久前蓝点网还有汇总的电视视频节目可以看，好怀念啊。
分析的很专业！
您没有考虑 树的根节点是负数的情况， 若树的根节点是个很大的负数，那么就要考虑过不过另外一边子树了
swap写成内联函数会不会好一些
写的好····· Pollard Rh
你指的哪个问题？
代码是给出了，但是解析的也太不清晰了吧！如 13 abejkcfghid jkebfghicda
第一步拆分为 三部分 (bejk, cfghi, d) * C(13,3)，为什么要这样拆分，原则是什么？
。。。
顶一个 赞一个
是穷举，但是代码有优化（v数组），并不是2^n。测试数据应该没问题，之前有超时的代码。
大哥，你复制也看看是不是这题的答案才复制吧。
为什么暴力求解方法循环到sqrt(n) 就可以了呢
可以根据二叉排序树的定义进行严格的排序树创建和后序遍历操作。如果形成的排序树相同，其树的前、中、后序遍历是相同的，但在此处不能使用中序遍历，因为，中序遍历的结果就是排序的结果。经在九度测试，运行时间90ms，比楼主的要快。
int L[m+1][n+1];这样定义出错，这个在gcc上可以编译通过 在VS上不行 应该改为new 或者vector
能告诉我为什么对于每一个m，cnt的值不用更新吗?这儿我想不通啊，谢谢


In the Hello World example, the text replaced was associated with an HTML element; specifically, the <p> element. It didn't have to be the <p> element; it could have been any element. But what if the text that needs to be replaced is not delimited by an HTML element?
The bad news is that Dynamator requires an HTML element. It can't locate arbitrary text. The good news is that there is an HTML 4.0 element created specifically for this purpose: <span>. The <span> element can be used to wrap arbitrary text. According to the HTML spec, <span> has no effect on the rendered browser output.
This example extends the original Hello World example slightly.
Once marked up with a <span> element, the file looks like this:
Because this file uses the same ID value as the original HelloWorld example, and the behavior is the same, we could use the same Dynamator file. But because Dynamator expects the Dynamator file to have the same base name as the HTML file, we need to create a file with the name 'ArbitraryText.dyn'. This file could use the directive '<include file="HelloWorld.dyn"/> to reuse the original content.
As in the first example, the HTML file needs to be processed by dynamate:
prompt=> java dynamate ArbitraryText.html
The above command produces the following file. Changes to the original HTML are highlighted.
If you are viewing this page in a servlet engine, you can see the generated page in action.
Because they provide a structured way to address arbitrary portions of an HTML document, the <span> and <div< elements are essential to site building with Dynamator.
This lesson only hints at an extremely powerful capability of Dynamator. Dynamator's loose coupling to HTML and it's <include> mechanism, combined with a strong naming convention, can enable a tremendous degree of reuse.


Introduction
Step 1
Step 2
Step 3
Step 4
Conclusion
Magnets are everywhere. If you have ever used a computer, microwave oven, copy machine or stereo speakers, you have used magnets!
Magnets can also be used to make electricity.
Think about it!
What is the biggest magnet around? Use the hints below to figure it out and then highlight the box to see if you were correct.
What is a magnet, anyway?
A magnet is something that has magnetic force.
The next question is "What is a magnetic force?" A magnetic force attracts iron and steel.
Magnets are materials that attract iron and steel.
There are many different types of magnets. Natural magnets occur naturally in nature. The mineral magnetite is a natural magnet. It can attract iron.
A temporary magnet is a magnet that has magnetic force for a short time. You can make a temporary magnet.


{{ report.analysis_system.verbose_name }}
| Report ID |
{{ report.id }} |
| Report status |
{% if report.status == 0 %}
Analysis completed without errors
{% elif report.status == 1 %}
Analysis completed with errors
{% else %}
Unknown analysis result status
{% endif %}
|
| API Link |
View report metadata in REST API |
| Report upload date |
{{ report.upload_date }} |
| Report analysis date |
{{ report.analysis_date }} |
| Tags |
{% for tag in report.tags %}
{{ tag }}
{% else %}
No tags found
{% endfor %}
|
No detailed visualization is available for this report type. A generic representation of the report contents follows.
Additional report metadata
{% for key, value in report.additional_metadata.items() %}
| {{ key }} | {{ value }} |
{% else %}
| No data found |
{% endfor %}
JSON report objects
{% for obj in report.json_report_objects %}
| {{ obj }} | View in REST API |
{% else %}
| No objects found |
{% endfor %}
Raw report objects
{% for obj in report.raw_report_objects %}
| {{ obj }} | Download file |
{% else %}
| No objects found |
{% endfor %}


| Mode | Callsign | Target | Source | Dur (s) |
|---|
| Time (UTC) | Mode | Callsign | Target | Source | Dur (s) | Loss | BER | QSO |
|---|---|---|---|---|---|---|---|---|
| Time (UTC) | Mode | Callsign | Target | Source | Dur (s) | BER |
|---|
| Callsign | Added at |
|---|
This Dashboard uses websockets-technology to transfer data from host to client. It actually uses the logfile of the MMDVMHost by G4KLX to get the entries into the different tables.
If you have any ideas or issues feel free to leave a comment/issue in github.


“Thanks for the advice during today’s webinar. It was exactly what I needed to hear.”-Tamika, Digital Reporter
“You had such great insight in class on workplace environments and employee/supervisor interaction.”-John, Engineer, Natus
“Thank you for presenting on the change management and leadership topics. Your presentation is helping me re-evaluate my approach to implementing change.”-Aruna, Quality Engineer
“Wow! You were amazing yesterday. You did such a good job!  We definitely will be you inviting you back again.”-Denise, Executive Director, Muckleshoot Tribal College


seniledawdler wrote:You can get to the change log from the bblog options in battlelog. It's just under the "BETTER BATTLELOG versionnumberhere" text.
http://getbblog.com/en/changelog
I agree it would be nice to have a link to it on the site also. Maybe in the news post that announces the new version.
seniledawdler wrote:I agree it would be nice to have a link to it on the site also. Maybe in the news post that announces the new version.


%settitle Resource {xtitle} - Search Parameters%>
<%file newheader%> <%file newnavbar%> <%resheader search%>| <%wgt%> Work Group | Maturity Level: N/A | <%sstatus%> | <%sec-cat%> | <%complinks%> |
Search parameters for the <%title%> resource. Also check the Extensions registry for search parameters on extensions related to this resource.
The common parameters also apply. See Searching for more information about searching in REST, messaging, and services.


{{ $baseURL := .Site.BaseURL }} {{ partial "head_material.html" . }}
404
Well, this isn't cool...
the thing you want isn't there
you might try starting here:
Home


Before Change
self.grid_bounds = grid_bounds
if grid is None:
grid = torch.zeros(len(grid_bounds), grid_size)
for i in range(len(grid_bounds)):
grid_diff = float(grid_bounds[i][1] - grid_bounds[i][0]) / (grid_size - 2)
grid[i] = torch.linspace(grid_bounds[i][0] - grid_diff,
grid_bounds[i][1] + grid_diff,
After Change
self.base_kernel_module = base_kernel_module
self.grid_size = grid_size
self.register_buffer("grid", grid)
self.register_buffer("_inducing_points", inducing_points)
def train(self, mode=True):
if hasattr(self, "_cached_kernel_mat"):
del self._cached_kernel_mat


---
layout: archive
title: Lean Prover Zulip Chat Archive
permalink: 113488general/45155monadonarbitrarycategories.html
---
The archive URL format has changed. Please find this page at:
https://leanprover-community.github.io/archive/stream/113488-general/topic/monad.20on.20arbitrary.20categories.html


--- title: Dynamic Content in a Statically Generated Site date: 2017-03-15 09:00:00 Z permalink: "/dynamic-content/" layout: single author_profile: true type: pages sidebar: nav: core_sidenav ---
I migrated this site a the static site generator ('Jekyll') last year. This means that the overall site and it's complexities are managed and trackable via a version control system (such as GitHub) and generated by a build process, rather than being dependent on server side processes and database lookups.
However it does mean that even simple content updates require me to update the code, and to commit the update to my code repository to trigger the build system to regenerate my site's updated content.
If I could augment this static site with dynamic content - it would enable me to more easily make content udpates and to potentially share the content curation process with more business focused (less technical) members of the team. To achieve this I'll be using a Dynamic Content System to inject the updated content, while utilising a secondary system for content updates and publishing mechansisms, to give me the best of both worlds. If such a dynamic content system has been architected to run headless (i.e. the content and presentation layers are decoupled) then I can also utilise this content in other channels, for example if I wanted to share this content with my native iOS and Android apps, or perhaps as part of my social media publishing workflows.
The section above is (with the pink background) is being managed by, and published, from Amplience Dynamic Content and dynamically loaded, though for pages where the content would benefit from being refreshed more frequently I could have much more of the page content be driven by the dynamic content system. Another approach might be to include some of this content into the build process, so that some of the content is included from the server-side process - which might give better access to content for search engine crawlers.
While this example just uses some simple text content elements, we can easily build a comprehensive library of content types, for use in all digital channels.
For this example I load the dynamic content asynchronously and then use the Moustache templating language to dictate the presentational aspects as mapped to the given pieces of the received structured content.
{% raw %}

{{ dynamic_content_title }}

{{ dynamic_content_paragraph1 }}

{% endraw %}
** Note: as jekyll also uses curly braces { } for it's templating language, you must wrap your moustache logic in {% raw %} to avoid it being interpreted by Jekyll.


|
Question 15:
Write a program called larg that prints out the
last character of every argument given on the command line.
Here are some examples: UNIX> larg UNIX> larg Jim Plank m k UNIX>larg 1 2 3 4 50 1 2 3 4 0 UNIX> |
Question 16:
Write a program revn that takes two command line arguments
-- an integer n and a filename fn.
It then makes the file fn, which is the first n lines
of standard input in reverse order. You may not use the stacks library
that we talked about in class on tuesday -- just use an array instead.
Here are some examples (I've bold-faced the output): UNIX> revn usage: revn n filename UNIX> revn 10 f1 f2 usage: revn n filename UNIX> revn 2 f1 Give Him Six! < CNTL-D > UNIX> cat f1 Him Give UNIX> revn 15 f2 Give Him Six! < CNTL-D > UNIX> cat f2 Six! Him Give UNIX> revn Jim Plank Bad value of n UNIX> revn -3 f3 Bad value of n UNIX>The answer sheet has a skeleton of the code for you to fill in. Obviously, if you can't do it all, do what you can so you can get partial credit. It helps in grading if you let me know what parts you didn't do. |


use Red::AST::Unary; use Red::AST::Value; unit class Red::AST::Generic::Postfix does Red::AST::Unary; has Str $.op is required; has $.returns; has $.value; method should-set(--> Hash()) { self.find-column-name => self.find-value } method should-validate {} method find-column-name { gather for self.args { .take for .?find-column-name } } method find-value { for self.args { .return with .?find-value } } method new($value, Str :$op, :$returns, Bool :$bind) { self.bless: :value(ast-value $value), :$op, :$returns, :$bind }


--- layout: default title: Alex Shvid ---
As a Data Grid Architect I'm interested in meeting a challenge of real complicated engagements specialized in high-load, bigdata and cloud computing. I've participated in mission critical projects and delivered multi-tenant architecture solutions. The sphere of my interests includes real time applications, low latency systems, open source and cloud orchestration solutions.


SYMON - System Monitoring Utility
Processor
Manafacturer: N/A
Model: N/A
Cores: N/A
Operating System
OS:N/A
OS Build:N/A
Hostname:N/A
Motherboard
Manafacturer: N/A
Model: N/A
Version: N/A
Graphics
Manafacturer:N/A
Model:N/A
VRAM:N/AMB
Usage Monitor
Processor Usage:
N/A
%
Uptime(seconds):
N/A
Free Memory(GB):
N/A


{% extends 'layout.html' %} {% block content %}
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It's like giving gun to monkey... very dangerous
or Spider-man:
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If this site helps you have more fun at work and increased the number of laughs in your meetings - then it has done it's job


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Go to the first, previous, next, last section, table of contents.
GNU Fortran currently generates code that is object-compatible with
the f2c
converter.
Also, it avoids limitations in the current GBE, such as the
inability to generate a procedure with
multiple entry points, by generating code that is structured
differently (in terms of procedure names, scopes, arguments, and
so on) than might be expected.
As a result, writing code in other languages that calls on, is
called by, or shares in-memory data with g77
-compiled code generally
requires some understanding of the way g77
compiles code for
various constructs.
Similarly, using a debugger to debug g77
-compiled
code, even if that debugger supports native Fortran debugging, generally
requires this sort of information.
This section describes some of the basic information on how
g77
compiles code for constructs involving interfaces to other
languages and to debuggers.
Caution: Much or all of this information pertains to only the current
release of g77
, sometimes even to using certain compiler options
with g77
(such as `-fno-f2c').
Do not write code that depends on this
information without clearly marking said code as nonportable and
subject to review for every new release of g77
.
This information
is provided primarily to make debugging of code generated by this
particular release of g77
easier for the user, and partly to make
writing (generally nonportable) interface code easier.
Both of these
activities require tracking changes in new version of g77
as they
are installed, because new versions can change the behaviors
described in this section.
g77
compiles a main program unit.
g77
constructs parameter lists
for procedures.
EQUIVALENCE
while debugging.
g77
performs complex arithmetic.
g77
implements alternate ENTRY
.
g77
handles alternate returns.
g77
handles ASSIGN
.
IOSTAT=
values.
When g77
compiles a main program unit, it gives it the public
procedure name MAIN__
.
The libg2c
library has the actual main()
procedure
as is typical of C-based environments, and
it is this procedure that performs some initial start-up
activity and then calls MAIN__
.
Generally, g77
and libg2c
are designed so that you need not
include a main program unit written in Fortran in your program--it
can be written in C or some other language.
Especially for I/O handling, this is the case, although g77
version 0.5.16
includes a bug fix for libg2c
that solved a problem with using the
OPEN
statement as the first Fortran I/O activity in a program
without a Fortran main program unit.
However, if you don't intend to use g77
(or f2c
) to compile
your main program unit--that is, if you intend to compile a main()
procedure using some other language--you should carefully
examine the code for main()
in libg2c
, found in the source
file `egcs/libf2c/libF77/main.c', to see what kinds of things
might need to be done by your main()
in order to provide the
Fortran environment your Fortran code is expecting.
For example, libg2c
's main()
sets up the information used by
the IARGC
and GETARG
intrinsics.
Bypassing libg2c
's main()
without providing a substitute for this activity would mean
that invoking IARGC
and GETARG
would produce undefined
results.
When debugging, one implication of the fact that main()
, which
is the place where the debugged program "starts" from the
debugger's point of view, is in libg2c
is that you won't be
starting your Fortran program at a point you recognize as your
Fortran code.
The standard way to get around this problem is to set a break
point (a one-time, or temporary, break point will do) at
the entrance to MAIN__
, and then run the program.
A convenient way to do so is to add the gdb
command
tbreak MAIN__
to the file `.gdbinit' in the directory in which you're debugging
(using gdb
).
After doing this, the debugger will see the current execution point of the program as at the beginning of the main program unit of your program.
Of course, if you really want to set a break point at some
other place in your program and just start the program
running, without first breaking at MAIN__
,
that should work fine.
Currently, g77
passes arguments via reference--specifically,
by passing a pointer to the location in memory of a variable, array,
array element, a temporary location that holds the result of evaluating an
expression, or a temporary or permanent location that holds the value
of a constant.
Procedures that accept CHARACTER
arguments are implemented by
g77
so that each CHARACTER
argument has two actual arguments.
The first argument occupies the expected position in the argument list and has the user-specified name. This argument is a pointer to an array of characters, passed by the caller.
The second argument is appended to the end of the user-specified
calling sequence and is named `__g77_length_x', where x
is the user-specified name.
This argument is of the C type ftnlen
(see `egcs/libf2c/g2c.h.in' for information on that type) and
is the number of characters the caller has allocated in the
array pointed to by the first argument.
A procedure will ignore the length argument if `X' is not declared
CHARACTER*(*)
, because for other declarations, it knows the
length.
Not all callers necessarily "know" this, however, which
is why they all pass the extra argument.
The contents of the CHARACTER
argument are specified by the
address passed in the first argument (named after it).
The procedure can read or write these contents as appropriate.
When more than one CHARACTER
argument is present in the argument
list, the length arguments are appended in the order
the original arguments appear.
So `CALL FOO('HI','THERE')' is implemented in
C as `foo("hi","there",2,5);', ignoring the fact that g77
does not provide the trailing null bytes on the constant
strings (f2c
does provide them, but they are unnecessary in
a Fortran environment, and you should not expect them to be
there).
Note that the above information applies to CHARACTER
variables and
arrays only.
It does not apply to external CHARACTER
functions or to intrinsic CHARACTER
functions.
That is, no second length argument is passed to `FOO' in this case:
CHARACTER X EXTERNAL X CALL FOO(X)
Nor does `FOO' expect such an argument in this case:
SUBROUTINE FOO(X) CHARACTER X EXTERNAL X
Because of this implementation detail, if a program has a bug
such that there is disagreement as to whether an argument is
a procedure, and the type of the argument is CHARACTER
, subtle
symptoms might appear.
g77
handles in a special way functions that return the following
types:
CHARACTER
COMPLEX
REAL(KIND=1)
For CHARACTER
, g77
implements a subroutine (a C function
returning void
)
with two arguments prepended: `__g77_result', which the caller passes
as a pointer to a char
array expected to hold the return value,
and `__g77_length', which the caller passes as an ftnlen
value
specifying the length of the return value as declared in the calling
program.
For CHARACTER*(*)
, the called function uses `__g77_length'
to determine the size of the array that `__g77_result' points to;
otherwise, it ignores that argument.
For COMPLEX
, when `-ff2c' is in
force, g77
implements
a subroutine with one argument prepended: `__g77_result', which the
caller passes as a pointer to a variable of the type of the function.
The called function writes the return value into this variable instead
of returning it as a function value.
When `-fno-f2c' is in force,
g77
implements a COMPLEX
function as gcc
's
`__complex__ float' or `__complex__ double' function
(or an emulation thereof, when `-femulate-complex' is in effect),
returning the result of the function in the same way as gcc
would.
For REAL(KIND=1)
, when `-ff2c' is in force, g77
implements
a function that actually returns REAL(KIND=2)
(typically
C's double
type).
When `-fno-f2c' is in force, REAL(KIND=1)
functions return float
.
Fortran permits each implementation to decide how to represent names as far as how they're seen in other contexts, such as debuggers and when interfacing to other languages, and especially as far as how casing is handled.
External names--names of entities that are public, or "accessible",
to all modules in a program--normally have an underscore (`_')
appended by g77
,
to generate code that is compatible with f2c
.
External names include names of Fortran things like common blocks,
external procedures (subroutines and functions, but not including
statement functions, which are internal procedures), and entry point
names.
However, use of the `-fno-underscoring' option disables this kind of transformation of external names (though inhibiting the transformation certainly improves the chances of colliding with incompatible externals written in other languages--but that might be intentional.
When `-funderscoring' is in force, any name (external or local)
that already has at least one underscore in it is
implemented by g77
by appending two underscores.
(This second underscore can be disabled via the
`-fno-second-underscore' option.)
External names are changed this way for f2c
compatibility.
Local names are changed this way to avoid collisions with external names
that are different in the source code---f2c
does the same thing, but
there's no compatibility issue there except for user expectations while
debugging.
For example:
Max_Cost = 0
Here, a user would, in the debugger, refer to this variable using the
name `max_cost__' (or `MAX_COST__' or `Max_Cost__',
as described below).
(We hope to improve g77
in this regard in the future--don't
write scripts depending on this behavior!
Also, consider experimenting with the `-fno-underscoring'
option to try out debugging without having to massage names by
hand like this.)
g77
provides a number of command-line options that allow the user
to control how case mapping is handled for source files.
The default is the traditional UNIX model for Fortran compilers--names
are mapped to lower case.
Other command-line options can be specified to map names to upper
case, or to leave them exactly as written in the source file.
For example:
Foo = 9.436
Here, it is normally the case that the variable assigned will be named `foo'. This would be the name to enter when using a debugger to access the variable.
However, depending on the command-line options specified, the
name implemented by g77
might instead be `FOO' or even
`Foo', thus affecting how debugging is done.
Also:
Call Foo
This would normally call a procedure that, if it were in a separate C program, be defined starting with the line:
void foo_()
However, g77
command-line options could be used to change the casing
of names, resulting in the name `FOO_' or `Foo_' being given to the
procedure instead of `foo_', and the `-fno-underscoring' option
could be used to inhibit the appending of the underscore to the name.
g77
names and lays out COMMON
areas
the same way f2c
does,
for compatibility with f2c
.
Currently, g77
does not emit "true" debugging information for
members of a COMMON
area, due to an apparent bug in the GBE.
(As of Version 0.5.19, g77
emits debugging information for such
members in the form of a constant string specifying the base name of
the aggregate area and the offset of the member in bytes from the start
of the area.
Use the `-fdebug-kludge' option to enable this behavior.
In gdb
, use `set language c' before printing the value
of the member, then `set language fortran' to restore the default
language, since gdb
doesn't provide a way to print a readable
version of a character string in Fortran language mode.
This kludge will be removed in a future version of g77
that,
in conjunction with a contemporary version of gdb
,
properly supports Fortran-language debugging, including access
to members of COMMON
areas.)
See section Options for Code Generation Conventions, for information on the `-fdebug-kludge' option.
Moreover, g77
currently implements a COMMON
area such that its
type is an array of the C char
data type.
So, when debugging, you must know the offset into a COMMON
area
for a particular item in that area, and you have to take into
account the appropriate multiplier for the respective sizes
of the types (as declared in your code) for the items preceding
the item in question as compared to the size of the char
type.
For example, using default implicit typing, the statement
COMMON I(15), R(20), T
results in a public 144-byte char
array named `_BLNK__'
with `I' placed at `_BLNK__[0]', `R' at `_BLNK__[60]',
and `T' at `_BLNK__[140]'.
(This is assuming that the target machine for
the compilation has 4-byte INTEGER(KIND=1)
and REAL(KIND=1)
types.)
g77
treats storage-associated areas involving a COMMON
block as explained in the section on common blocks.
A local EQUIVALENCE
area is a collection of variables and arrays
connected to each other in any way via EQUIVALENCE
, none of which are
listed in a COMMON
statement.
Currently, g77
does not emit "true" debugging information for
members in a local EQUIVALENCE
area, due to an apparent bug in the GBE.
(As of Version 0.5.19, g77
does emit debugging information for such
members in the form of a constant string specifying the base name of
the aggregate area and the offset of the member in bytes from the start
of the area.
Use the `-fdebug-kludge' option to enable this behavior.
In gdb
, use `set language c' before printing the value
of the member, then `set language fortran' to restore the default
language, since gdb
doesn't provide a way to print a readable
version of a character string in Fortran language mode.
This kludge will be removed in a future version of g77
that,
in conjunction with a contemporary version of gdb
,
properly supports Fortran-language debugging, including access
to members of EQUIVALENCE
areas.)
See section Options for Code Generation Conventions, for information on the `-fdebug-kludge' option.
Moreover, g77
implements a local EQUIVALENCE
area such that its
type is an array of the C char
data type.
The name g77
gives this array of char
type is `__g77_equiv_x',
where x is the name of the item that is placed at the beginning (offset 0)
of this array.
If more than one such item is placed at the beginning, x is
the name that sorts to the top in an alphabetical sort of the list of
such items.
When debugging, you must therefore access members of EQUIVALENCE
areas by specifying the appropriate `__g77_equiv_x'
array section with the appropriate offset.
See the explanation of debugging COMMON
blocks
for info applicable to debugging local EQUIVALENCE
areas.
(Note: g77
version 0.5.18 and earlier chose the name
for x using a different method when more than one name was
in the list of names of entities placed at the beginning of the
array.
Though the documentation specified that the first name listed in
the EQUIVALENCE
statements was chosen for x, g77
in fact chose the name using a method that was so complicated,
it seemed easier to change it to an alphabetical sort than to describe the
previous method in the documentation.)
As of 0.5.20, g77
defaults to handling COMPLEX
types
(and related intrinsics, constants, functions, and so on)
in a manner that
makes direct debugging involving these types in Fortran
language mode difficult.
Essentially, g77
implements these types using an
internal construct similar to C's struct
, at least
as seen by the gcc
back end.
Currently, the back end, when outputting debugging info with
the compiled code for the assembler to digest, does not detect
these struct
types as being substitutes for Fortran
complex.
As a result, the Fortran language modes of debuggers such as
gdb
see these types as C struct
types, which
they might or might not support.
Until this is fixed, switch to C language mode to work with
entities of COMPLEX
type and then switch back to Fortran language
mode afterward.
(In gdb
, this is accomplished via `set lang c' and
either `set lang fortran' or `set lang auto'.)
Fortran uses "column-major ordering" in its arrays. This differs from other languages, such as C, which use "row-major ordering". The difference is that, with Fortran, array elements adjacent to each other in memory differ in the first subscript instead of the last; `A(5,10,20)' immediately follows `A(4,10,20)', whereas with row-major ordering it would follow `A(5,10,19)'.
This consideration affects not only interfacing with and debugging Fortran code, it can greatly affect how code is designed and written, especially when code speed and size is a concern.
Fortran also differs from C, a popular language for interfacing and to support directly in debuggers, in the way arrays are treated. In C, arrays are single-dimensional and have interesting relationships to pointers, neither of which is true for Fortran. As a result, dealing with Fortran arrays from within an environment limited to C concepts can be challenging.
For example, accessing the array element `A(5,10,20)' is easy enough in Fortran (use `A(5,10,20)'), but in C some difficult machinations are needed. First, C would treat the A array as a single-dimension array. Second, C does not understand low bounds for arrays as does Fortran. Third, C assumes a low bound of zero (0), while Fortran defaults to a low bound of one (1) and can supports an arbitrary low bound. Therefore, calculations must be done to determine what the C equivalent of `A(5,10,20)' would be, and these calculations require knowing the dimensions of `A'.
For `DIMENSION A(2:11,21,0:29)', the calculation of the offset of `A(5,10,20)' would be:
(5-2) + (10-1)*(11-2+1) + (20-0)*(11-2+1)*(21-1+1) = 4293
So the C equivalent in this case would be `a[4293]'.
When using a debugger directly on Fortran code, the C equivalent
might not work, because some debuggers cannot understand the notion
of low bounds other than zero. However, unlike f2c
, g77
does inform the GBE that a multi-dimensional array (like `A'
in the above example) is really multi-dimensional, rather than a
single-dimensional array, so at least the dimensionality of the array
is preserved.
Debuggers that understand Fortran should have no trouble with non-zero low bounds, but for non-Fortran debuggers, especially C debuggers, the above example might have a C equivalent of `a[4305]'. This calculation is arrived at by eliminating the subtraction of the lower bound in the first parenthesized expression on each line--that is, for `(5-2)' substitute `(5)', for `(10-1)' substitute `(10)', and for `(20-0)' substitute `(20)'. Actually, the implication of this can be that the expression `*(&a[2][1][0] + 4293)' works fine, but that `a[20][10][5]' produces the equivalent of `*(&a[0][0][0] + 4305)' because of the missing lower bounds.
Come to think of it, perhaps the behavior is due to the debugger internally compensating for the lower bounds by offsetting the base address of `a', leaving `&a' set lower, in this case, than `&a[2][1][0]' (the address of its first element as identified by subscripts equal to the corresponding lower bounds).
You know, maybe nobody really needs to use arrays.
Adjustable and automatic arrays in Fortran require the implementation
(in this
case, the g77
compiler) to "memorize" the expressions that
dimension the arrays each time the procedure is invoked.
This is so that subsequent changes to variables used in those
expressions, made during execution of the procedure, do not
have any effect on the dimensions of those arrays.
For example:
REAL ARRAY(5) DATA ARRAY/5*2/ CALL X(ARRAY, 5) END SUBROUTINE X(A, N) DIMENSION A(N) N = 20 PRINT *, N, A END
Here, the implementation should, when running the program, print something like:
20 2. 2. 2. 2. 2.
Note that this shows that while the value of `N' was successfully changed, the size of the `A' array remained at 5 elements.
To support this, g77
generates code that executes before any user
code (and before the internally generated computed GOTO
to handle
alternate entry points, as described below) that evaluates each
(nonconstant) expression in the list of subscripts for an
array, and saves the result of each such evaluation to be used when
determining the size of the array (instead of re-evaluating the
expressions).
So, in the above example, when `X' is first invoked, code is executed that copies the value of `N' to a temporary. And that same temporary serves as the actual high bound for the single dimension of the `A' array (the low bound being the constant 1). Since the user program cannot (legitimately) change the value of the temporary during execution of the procedure, the size of the array remains constant during each invocation.
For alternate entry points, the code g77
generates takes into
account the possibility that a dummy adjustable array is not actually
passed to the actual entry point being invoked at that time.
In that case, the public procedure implementing the entry point
passes to the master private procedure implementing all the
code for the entry points a NULL
pointer where a pointer to that
adjustable array would be expected.
The g77
-generated code
doesn't attempt to evaluate any of the expressions in the subscripts
for an array if the pointer to that array is NULL
at run time in
such cases.
(Don't depend on this particular implementation
by writing code that purposely passes NULL
pointers where the
callee expects adjustable arrays, even if you know the callee
won't reference the arrays--nor should you pass NULL
pointers
for any dummy arguments used in calculating the bounds of such
arrays or leave undefined any values used for that purpose in
COMMON--because the way g77
implements these things might
change in the future!)
The GBE does not understand the general concept of
alternate entry points as Fortran provides via the ENTRY statement.
g77
gets around this by using an approach to compiling procedures
having at least one ENTRY
statement that is almost identical to the
approach used by f2c
.
(An alternate approach could be used that
would probably generate faster, but larger, code that would also
be a bit easier to debug.)
Information on how g77
implements ENTRY
is provided for those
trying to debug such code.
The choice of implementation seems
unlikely to affect code (compiled in other languages) that interfaces
to such code.
g77
compiles exactly one public procedure for the primary entry
point of a procedure plus each ENTRY
point it specifies, as usual.
That is, in terms of the public interface, there is no difference
between
SUBROUTINE X END SUBROUTINE Y END
and:
SUBROUTINE X ENTRY Y END
The difference between the above two cases lies in the code compiled for the `X' and `Y' procedures themselves, plus the fact that, for the second case, an extra internal procedure is compiled.
For every Fortran procedure with at least one ENTRY
statement, g77
compiles an extra procedure
named `__g77_masterfun_x', where x is
the name of the primary entry point (which, in the above case,
using the standard compiler options, would be `x_' in C).
This extra procedure is compiled as a private procedure--that is, a procedure not accessible by name to separately compiled modules. It contains all the code in the program unit, including the code for the primary entry point plus for every entry point. (The code for each public procedure is quite short, and explained later.)
The extra procedure has some other interesting characteristics.
The argument list for this procedure is invented by g77
.
It contains
a single integer argument named `__g77_which_entrypoint',
passed by value (as in Fortran's `%VAL()' intrinsic), specifying the
entry point index--0 for the primary entry point, 1 for the
first entry point (the first ENTRY
statement encountered), 2 for
the second entry point, and so on.
It also contains, for functions returning CHARACTER
and
(when `-ff2c' is in effect) COMPLEX
functions,
and for functions returning different types among the
ENTRY
statements (e.g. `REAL FUNCTION R()'
containing `ENTRY I()'), an argument named `__g77_result' that
is expected at run time to contain a pointer to where to store
the result of the entry point.
For CHARACTER
functions, this
storage area is an array of the appropriate number of characters;
for COMPLEX
functions, it is the appropriate area for the return
type; for multiple-return-type functions, it is a union of all the supported return
types (which cannot include CHARACTER
, since combining CHARACTER
and non-CHARACTER
return types via ENTRY
in a single function
is not supported by g77
).
For CHARACTER
functions, the `__g77_result' argument is followed
by yet another argument named `__g77_length' that, at run time,
specifies the caller's expected length of the returned value.
Note that only CHARACTER*(*)
functions and entry points actually
make use of this argument, even though it is always passed by
all callers of public CHARACTER
functions (since the caller does not
generally know whether such a function is CHARACTER*(*)
or whether
there are any other callers that don't have that information).
The rest of the argument list is the union of all the arguments
specified for all the entry points (in their usual forms, e.g.
CHARACTER
arguments have extra length arguments, all appended at
the end of this list).
This is considered the "master list" of
arguments.
The code for this procedure has, before the code for the first executable statement, code much like that for the following Fortran statement:
GOTO (100000,100001,100002), __g77_which_entrypoint 100000 ...code for primary entry point... 100001 ...code immediately following first ENTRY statement... 100002 ...code immediately following second ENTRY statement...
(Note that invalid Fortran statement labels and variable names
are used in the above example to highlight the fact that it
represents code generated by the g77
internals, not code to be
written by the user.)
It is this code that, when the procedure is called, picks which entry point to start executing.
Getting back to the public procedures (`x' and `Y' in the original
example), those procedures are fairly simple.
Their interfaces
are just like they would be if they were self-contained procedures
(without ENTRY
), of course, since that is what the callers
expect.
Their code consists of simply calling the private
procedure, described above, with the appropriate extra arguments
(the entry point index, and perhaps a pointer to a multiple-type-
return variable, local to the public procedure, that contains
all the supported returnable non-character types).
For arguments
that are not listed for a given entry point that are listed for
other entry points, and therefore that are in the "master list"
for the private procedure, null pointers (in C, the NULL
macro)
are passed.
Also, for entry points that are part of a multiple-type-
returning function, code is compiled after the call of the private
procedure to extract from the multi-type union the appropriate result,
depending on the type of the entry point in question, returning
that result to the original caller.
When debugging a procedure containing alternate entry points, you can either set a break point on the public procedure itself (e.g. a break point on `X' or `Y') or on the private procedure that contains most of the pertinent code (e.g. `__g77_masterfun_x'). If you do the former, you should use the debugger's command to "step into" the called procedure to get to the actual code; with the latter approach, the break point leaves you right at the actual code, skipping over the public entry point and its call to the private procedure (unless you have set a break point there as well, of course).
Further, the list of dummy arguments that is visible when the private procedure is active is going to be the expanded version of the list for whichever particular entry point is active, as explained above, and the way in which return values are handled might well be different from how they would be handled for an equivalent single-entry function.
Subroutines with alternate returns (e.g. `SUBROUTINE X(*)' and
`CALL X(*50)') are implemented by g77
as functions returning
the C int
type.
The actual alternate-return arguments are omitted from the calling sequence.
Instead, the caller uses
the return value to do a rough equivalent of the Fortran
computed-GOTO
statement, as in `GOTO (50), X()' in the
example above (where `X' is quietly declared as an INTEGER(KIND=1)
function), and the callee just returns whatever integer
is specified in the RETURN
statement for the subroutine
For example, `RETURN 1' is implemented as `X = 1' followed
by `RETURN'
in C, and `RETURN' by itself is `X = 0' and `RETURN').
For portability to machines where a pointer (such as to a label,
which is how g77
implements ASSIGN
and its relatives,
the assigned-GOTO
and assigned-FORMAT
-I/O statements)
is wider (bitwise) than an INTEGER(KIND=1)
, g77
uses a different memory location to hold the ASSIGN
ed value of a variable
than it does the numerical value in that variable, unless the
variable is wide enough (can hold enough bits).
In particular, while g77
implements
I = 10
as, in C notation, `i = 10;', it implements
ASSIGN 10 TO I
as, in GNU's extended C notation (for the label syntax),
`__g77_ASSIGN_I = &&L10;' (where `L10' is just a massaging
of the Fortran label `10' to make the syntax C-like; g77
doesn't
actually generate the name `L10' or any other name like that,
since debuggers cannot access labels anyway).
While this currently means that an ASSIGN
statement does not
overwrite the numeric contents of its target variable, do not
write any code depending on this feature.
g77
has already changed this implementation across
versions and might do so in the future.
This information is provided only to make debugging Fortran programs
compiled with the current version of g77
somewhat easier.
If there's no debugger-visible variable named `__g77_ASSIGN_I'
in a program unit that does `ASSIGN 10 TO I', that probably
means g77
has decided it can store the pointer to the label directly
into `I' itself.
See section Ugly Assigned Labels, for information on a command-line option
to force g77
to use the same storage for both normal and
assigned-label uses of a variable.
The libg2c
library currently has the following table to relate
error code numbers, returned in IOSTAT=
variables, to messages.
This information should, in future versions of this document, be
expanded upon to include detailed descriptions of each message.
In line with good coding practices, any of the numbers in the
list below should not be directly written into Fortran
code you write.
Instead, make a separate INCLUDE
file that defines
PARAMETER
names for them, and use those in your code,
so you can more easily change the actual numbers in the future.
The information below is culled from the definition
of F_err
in `f/runtime/libI77/err.c' in the
g77
source tree.
100: "error in format" 101: "illegal unit number" 102: "formatted io not allowed" 103: "unformatted io not allowed" 104: "direct io not allowed" 105: "sequential io not allowed" 106: "can't backspace file" 107: "null file name" 108: "can't stat file" 109: "unit not connected" 110: "off end of record" 111: "truncation failed in endfile" 112: "incomprehensible list input" 113: "out of free space" 114: "unit not connected" 115: "read unexpected character" 116: "bad logical input field" 117: "bad variable type" 118: "bad namelist name" 119: "variable not in namelist" 120: "no end record" 121: "variable count incorrect" 122: "subscript for scalar variable" 123: "invalid array section" 124: "substring out of bounds" 125: "subscript out of bounds" 126: "can't read file" 127: "can't write file" 128: "'new' file exists" 129: "can't append to file" 130: "non-positive record number" 131: "I/O started while already doing I/O"
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DfE enquiries
Central newsdesk 020 7783 8300
General enquiries 0370 000 2288
Press release
Plans announced to help more people take up part-time learning and strengthen the numbers studying at a doctoral level at UK universities.
Two consultations have been published today (4 November 2016) on new student loans which will, for the first time, offer maintenance support for part-time learners and encourage more students to take up postgraduate study with doctoral loans worth up to £25,000 .
Two consultations on new student loans have been published today (4 November 2016). The loans will, for the first time, offer maintenance support for part-time learners and encourage more students to take up postgraduate study with doctoral loans worth up to £25,000 .
Providing further support for part-time undergraduate study will play an important role in helping students to develop the skills our economy needs. The proposed new maintenance loan will support part-time students for the first time, in addition to the fee loans on offer, and will help part-time students meet living costs.
We will also be consulting on new doctoral loans which will contribute up to £25,000 towards students’ cost of studies. This marks not only a substantial investment in the education and future of students, but will also continue to strengthen the UK’s research base as we work to cement our position as a world leader in new ideas and technologies.
Jo Johnson, Minister for Universities, Science, Research and Innovation said:
We want anyone, regardless of their circumstances, to have the option to study at degree level and beyond.
That’s why over the past 18 months we have completely overhauled financial support for postgraduate study and why we plan new support for part-time study at undergraduate level.
We have already introduced a new loan for postgraduate masters study which is helping thousands of people from all backgrounds study for an advanced qualification. Introducing new loans for part-time and doctoral students is an important next step in upgrading our skills and research base and arming people with the skills that employers are demanding up and down the country.
Evidence gathered through both consultations, will be used to inform:
This year the government introduced new loans for masters study which are already benefitting thousands of students from all backgrounds who want to study for an advanced qualification. The 2 consultations announced today represent the next step in government’s commitment to removing financial barriers to further study.
Central newsdesk 020 7783 8300
General enquiries 0370 000 2288
Published: 4 November 2016
From: Department for Education Jo Johnson MP
Part of: Access to higher education


Over the years the interest in the stamps has been falling to the point that what seemed like a safe value 30 years ago today has seen the price fall to unsuspected limits at that time.
It is now that for about five years it has been returning some interest in the face of falling prices. Great collectors take advantage of this juncture to complete collections and get stamps that once seemed very difficult. Although, the current market price is influenced by the ease with which today can falsify materials. But for a counterfeit to be so good that it can supplant the original, a lot of investment is needed and today even that investment is not profitable because of the scarce demand to acquire high value stamps.
To make matters worse many of the generations who collected stamps are now older and want to get rid of the stamps to finish their years in a more comfortable way.
That's where the real bargains are emerging since the professionals who buy do not even offer the amount that cost then to acquire them. These to pay for these collections sell their leftovers on the Internet or in the squares of towns or cities at very low prices.
No doubt when this bubble ends below, and start to have a market outside of Spain in those emerging countries that today are major powers such as India and China, all these stamps will return to take their place and will be absorbed by outsiders. Since the middle and upper middle classes grow at a good pace. Spain being a country so famous outside our borders and having so little population, shots of a million stamps will go from being large to ultra-short throws. Everything will come and there will have to be waiting for the moment ....
A postage stamp is a small piece of paper issued by a post office, postal administration, or other authorized vendors to customers who pay postage (the cost involved in moving, insuring, or registering mail), who then affix the stamp to the face or address-side of any item of mail—an envelope or other postal cover (e.g., packet, box, mailing cylinder)—that they wish to send. The item is then processed by the postal system, where a postmark or cancellation mark—in modern usage indicating date and point of origin of mailing—is applied to the stamp and its left and right sides to prevent its reuse. The item is then delivered to its addressee.
Always featuring the name of the issuing nation (with the exception of the United Kingdom), a denomination of its value, and often an illustration of persons, events, institutions, or natural realities that symbolize the nation's traditions and values, every stamp is printed on a piece of usually rectangular, but sometimes triangular or otherwise shaped special custom-made paper whose back is either glazed with an adhesive gum or self-adhesive.
Because governments issue stamps of different denominations in unequal numbers and routinely discontinue some lines and introduce others, and because of their illustrations and association with the social and political realities of the time of their issue, they are often prized for their beauty and historical significance by stamp collectors whose study of their history and of mailing systems is called philately. Because collectors often buy stamps from an issuing agency with no intention to use them for postage, the revenues from such purchases and payments of postage can make them a source of net profit to that agency.
[Fuente: WIKIPEDIA]
The issuance of the first postage stamp is part of a profound reform of the British postal service undertaken by James Chalmers (1834) and Rowland Hill (1837). Until then the shipment was paid by the recipient based on the kilometers traveled and not by weight. Hill proposed that the shipment be paid by the sender at a uniform rate based on weight and not mileage.
Previously stamps used to carry an engraving of the issuer of the stamp in which it contained the place of origin of the shipment and the date of the shipment was added. In addition, they used to have recorded the rate of the one that made the shipments with their corresponding tax.
This goes to say that a currency was normalized only to pay for shipments. That is why there was a large regulation and that this process will be carried out from the central administration. In the case of Spain from the Fabrica de Moneda y timbre. And is that the new stamps would have the same value as a currency while limiting the use to the same purpose. As of today, it is not possible to pay for normal goods on stamps, as it is not possible to pay with cryptocurrencies.
The stamps once spent a time began to have people who stored the stamps and collected and began to speculate with the value to some extent because there were stamps that were issued in large quantities and others in very few. That's where philately would come from.
De aquí cabría resaltar que tanto el dentado como el centrado influye mucho en el precio final del sello a coleccionar. A veces es casi del 50%, en sellos que suelen estar descentrados el centrado se considera raro de ahí que tenga más valor.
It is not true that you have to reach 50% but the seller will try to apply this percentage based on the official price catalog for the corresponding series.
Overloads are usually quoted in the catalog of stamps, with different series being overloaded and those that are not. This when it is an official overload because if it is not the seal will have lost its value being considered postmarked. And is that the stamps canceled generally lower the price of the seal around 90%.
Although as everything if the seal is very scarce either postmarked or will not have an intrinsic value.
Another factor to consider is whether it is a stamp that by mistake has been printed different from the original series. These seals tend to be scarce because the defect in the printing press is corrected immediately and for that reason they are worth much more than the original ones.
As an example, it is worth highlighting the ruling a year ago in which the cathedral of Burgos appeared on the seal of León This would be used by a multitude of speculators to get hold of all those who picked up the error.
Recently, interest in stamps has been lost, and there are many people interested in getting rid of their collections. This is because the people who started collecting stamps would be in the 50s-60s. These people are already very old and many want to enjoy their investment. However, the stamps are in decline, their use is testimonial and is limited almost to parcel shipments because the sending of letters with new technologies has almost completely disappeared. If perhaps people with a tradition of sending Christmas Christmas usually buy stamps.
A esto se le añade los sellos ATM que son etiquetadas franqueadoras por correos en los que el valor del envío se imprime en el momento de matasellarlo. Estos sellos también se coleccionan y su uso es desde 1991 con lo que existen todavía muy pocas etiquetas diferentes si bien las tiradas han sido muy grandes, por lo que el valor es bien poco.
In the image on the right, several of these labels are shown. In the case of the left, a series of means of transport that were taken a posteriori since the former were based solely on the logo of the post office and they did not think about doing them exposing anything.
Later they would be grouped in series with some motive whether they are means of transport, animals, canvases, etc.
The use of labels would reduce the demand for stamps and to adjust supply and demand shorter runs would be made. This is a point in favor of modern stamps that are scarce and above all have been used less so that a modern stamp even postmarked is worth more than a stamp of 4 decades ago.
Los sellos más comunes son los de la cara del mandatario, Franco y Juan Carlos I y de valor nominal bajo. Si bien hay alguna excepción con una serie de colores que fueron tiradas más cortas que otras. A continuación muestro la tirada completa de los sellos del rey Juan Carlos de finales de los 70s.
I also show other seals of that decade, such as that of soldiers whose value is also scarce due to the large number of them.
Also since the 80s there is a tendency to make complete sheets that agglutinate a complete series. In collecting if these come without separating the price is higher.
An income, tax or fiscal stamp (in French, stamp, stamp) is a sticker commonly used to collect taxes or costs on documents, tobacco, alcoholic beverages, drugs and medicines, game cards, hunting licenses , firearms licenses, and many other things.
Tax stamps are stamps used to collect taxes and payments. The government is in charge of issuing them, be they national or local, as well as the official bodies of various classes. They have many shapes and can be adhesive or not, perforated or not, printed or embossed, and of any size.
In many countries, they are as detailed in their design as bills and are often made from the same type of paper. The high value of many tax stamps means that they can contain security devices to prevent counterfeiting.
These stamps were widely used in their origins, existing a lot of variant. There are catalogs specialized in this type of stamps. At first they were collected like the rest of the stamps but later they would be out of the official catalog.
The stamps on the right are part of my collection and I have some replicas of old paper stamps of the first prosecutors (1870 onwards) with the allegory of the republic as those of the other sheet. In those there are from the times of Alfonso XII and Alfonso XIII until those of Franco with the Yoke and the arrows.
These stamps together with the prosecutors would be out of the catalog and would be part of the telegraphs. With time they have been recovering importance and value as a sample of our history.
In the nineteenth century Spain still had overseas territories such as Cuba and the Philippines and some other island and part of North Africa. In these territories, a Spanish stamp would be issued. The last colonies to be lost would be the north of Morocco, Ifni and Fernando Poo that they would do in Franco's time with the famous green march. As soon as stamps were no longer issued, they would charge more value, although due to the large printouts of the last stamps, only those prior to 1930 have real value.
Next I will show Ifni stamps (€ 0.10 unit, € 0.30 catalog) without great philatelic value and others from Morocco that have a lot more (€ 1-10 unit).
>Estos sellos al ser los primeros del catálogo EDIFIl son los que más valor tienen. Un sello de Isabel II de alto valor fácial (reales o escudos), puede costar una fortuna (de 1000 a 20000€).
While it is quite unlikely that you have them since these stamps are usually seen in auctions. They are falsifiable because if you rent make a careful copy, it is better to avoid collecting these relics.
Especially in new condition. Recall that 8 escudos formerly today would be about € 600 to € 1200 to change. 8 escudos would be the equivalent of 200 old pesetas. If you trace the analogy and add inflation since then you will have equivalence. 4 reales was the same as 1 peseta and 1 real equivalent to 34 maravedies (6 maravedies of 8) that I will explain when I talk about the Spanish monetary system and its history. So things a peseta 200 years ago would be a lot more than 50 euros today. On the other hand, Alfonso XIII would reduce the difference 4 or 5 times due to inflation.
Of these stamps it is best to have low series that were equivalent to cents and are quite cheap because the runs were large. A perfect stamp of low runs could leave for € 0.30 to give us an idea.
Regarding the seals of Alfonso XII and Alfonso XIII, the value drops considerably with respect to Isabel II and for just over 100 euros you can obtain the complete series in new from the last ones and in used from the first.
These stamps are part of the first 300 of the catalog of Spain that today 2019 has more than 5000.
Here are some of my collection:
These are perhaps the most beautiful stamps in the entire stamp collection. It is the time where great mastery in drawing and printing in the old style would have been achieved and the reasons illustrated are part of the best of Spanish culture (Goya painting, discovery of America, Cervantes, cathedrals, etc).
Its value today is between € 20 and € 300 for many of the series in the official catalog but due to the disinterest in buying these items are falling until you can buy up to 1/4 of the official value of the catalog or even less .
The most expensive are the series of railways or the aircraft with prices of up to € 800 for a series in perfect condition (good centering, with lots of color, rubber and no fixed).
Here I show some of my possession. They are between 400 and 600 of the EDIFIL numbering.
In the Spanish civil war there were many stamps with a very small period of use and different Spanish regions. In addition to having two sides in the war each had their own images on the stamps. The runs were so short that they have some much more value than those of Alfonso XIII. While the quality of the seal leaves much to be desired.
On the republican side reference is made to the values of the republic and to the image of the allegory of the republic. The images of presidents and politicians in office. On the national side the odes to Spain and the patriotic tone is what is most mentioned. Also images with high catholic connotation.
From the civil war the stamps have hardly any value except for a few exceptions with ultrashort runs like those of Legazpi and Sorolla that are around € 300 in official value although it is not difficult to obtain them for around € 30.
That is why I do not recommend registering at the Spanish philatelic company at all and paying € 40 to get the full year since today's stamps will never be revalued. Quite the opposite in a few years can be achieved at the same price then and with the rise in inflation you will be losing money.
It is only advisable to do with old series since most of the runs of these series do not exceed 300,000 units and one day will come that the interest of the new emerging countries such as China or India with millions of people, and hundreds of rich thousands will make these stamps go up a lot because of their scarcity.
Finally I will mention the stamps of other countries. Normally if you start collecting stamps it is normal to go for those of your country and then if there is something of interest or if you have a good chance to get some of the countries in your environment. In the images on the right are stamps of Italy from the first of the catalog with King Humberto I and those of Portugal. The price of stamps in these countries is much lower than the Spanish collection. While they have some fairly short new runs that cost a fortune.
To know the price there are many catalogs of which YVERT & TELLIER stands out.. This catalog contains all the existing stamps in the world. Due to the multitude of information it has several volumes and it is quite expensive if you buy an updated version. Although on the internet we can get an outdated catalog for a fraction of the price again.
Below I show some of the German empire, some of the old Germany that was separated into independent states. These stamps of the states are highly valued. Strong> In my case I only have three or four that are those in the first row.
In my case I got hold of several of our neighboring countries such as France, Portugal, Italy and Germany. And some other country than I have some stamps.
The seals of the German empire after the First World War are remarkable with the Republic of Weimar " in how they were scaling the price until a stamp could be worth several million Marcos.
Below I show how are the stamps with the highest nominal value that I have seen worth one billion which translates to thousand . These stamps would be used very little since they are part of the last months of the great scarcity crisis and their use would be anecdotal.
Later I would get a good collection of stamps from different countries in South America. On the right I show some of the oldest series in Mexico and some not so old. In particular, it is worth doing with old stamps and not new ones. The new stamps are overvalued and does not serve as a source of investment as with the Spanish stamps. Right now there are many sales with some of these stamps at a pretty good price compared to the value they can have attending the print run and the condition in which they are. That is why a good market for the one who understands. Yes, not investing more than one euro per stamp and trying to be at 10% -20% of the value of catalogs. Más tarde me haría con una buena colección de sellos de distintos países de Sudamérica. A la derecha muestro series de los más antiguos de México y algunos no tan antiguos.
En especial, vale la pena hacerse con sellos antiguos y no nuevos. Los sellos nuevos están sobrevalorados y no sirve de nada como fuente de inversión al igual que con los sellos españoles. Ahora mismo hay multitud de ventas con algunos de estos sellos a un precio bastante bueno en comparación con el valor que pueden tener atendiendo a la tirada y la condición en la que se encuentran. Es por ello un buen mercado para el que entienda. Eso sí, no invirtiendo más de un euro por sello y intentando que sea a un 10%-20% del valor de los catálogos.
For that reason, in these cases, I only invest in used stamps since, in my view, in several years the difference between new and used stamps will decrease.
The key is also to use it as a diversification of our long-term capital, not exceeding 2% of it in any case.
Here is a sample of the stamps of old Uruguay that I have that I made at a good price. Not having spent more than 20 euros for stamps that catalog prices could be around 200 euros.
On the other hand I show a lamina of stamps of the islands of Bermuda. There are many small states that emit a lot of stamps and that the state lives in part of philately because in the world there are a lot of people who collect all the stamps in the world. That is attractive since every year only with the issuance of stamps for this demand from outside the state earns a lot of money. I have many stamps but used whose value is very relative. I do not advise buying new stamps from these pseudo-states or tax havens like Bermuda, Cayman Islands, Antigua, etc. Only as a comment that there are countries that report large amounts of money.
Finally add that I have surplus albums of my purchases that I sell at a very good price. The stamp used around 0.03 € -0.05 € in packages of 1000 stamps adding the album where it is. If you are interested send an email to my address or in the same wallapop.
MI tienda en wallapop
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