1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
|
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>futurize: Py2 to Py2/3 — Python-Future documentation</title>
<link rel="stylesheet" href="_static/basic.css" type="text/css" />
<link rel="stylesheet" href="_static/pygments.css" type="text/css" />
<link rel="stylesheet" href="_static/my-styles.css" type="text/css" />
<link rel="stylesheet" href="_static/bootswatch-3.3.4/cerulean/bootstrap.min.css" type="text/css" />
<link rel="stylesheet" href="_static/bootstrap-sphinx.css" type="text/css" />
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT: './',
VERSION: '',
COLLAPSE_INDEX: false,
FILE_SUFFIX: '.html',
HAS_SOURCE: true
};
</script>
<script type="text/javascript" src="_static/jquery.js"></script>
<script type="text/javascript" src="_static/underscore.js"></script>
<script type="text/javascript" src="_static/doctools.js"></script>
<script type="text/javascript" src="_static/js/jquery-1.11.0.min.js"></script>
<script type="text/javascript" src="_static/js/jquery-fix.js"></script>
<script type="text/javascript" src="_static/bootstrap-3.3.4/js/bootstrap.min.js"></script>
<script type="text/javascript" src="_static/bootstrap-sphinx.js"></script>
<link rel="shortcut icon" href="_static/python-future-icon-32.ico"/>
<link rel="top" title="Python-Future documentation" href="index.html" />
<meta charset='utf-8'>
<meta http-equiv='X-UA-Compatible' content='IE=edge,chrome=1'>
<meta name='viewport' content='width=device-width, initial-scale=1.0, maximum-scale=1'>
<meta name="apple-mobile-web-app-capable" content="yes">
<script type="text/javascript">
var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-19344199-2']);
_gaq.push(['_trackPageview']);
</script>
</head>
<body role="document">
<a href="https://github.com/PythonCharmers/python-future"><img style="position: absolute; top: 45px; right: 0; border: 0;" src="https://s3.amazonaws.com/github/ribbons/forkme_right_orange_ff7600.png" alt="Fork me on GitHub"></a>
<div id="navbar" class="navbar navbar-inverse navbar-default navbar-fixed-top">
<div class="container">
<div class="navbar-header">
<!-- .btn-navbar is used as the toggle for collapsed navbar content -->
<button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".nav-collapse">
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<a class="logo"> <img height="32" width="32" src="_static/python-future-logo-textless-transparent.png" /></a>
<a class="navbar-brand" href="index.html">Python-Future</a>
<span class="navbar-text navbar-version pull-left"><b></b></span>
</div>
<div class="collapse navbar-collapse nav-collapse">
<ul class="nav navbar-nav">
<li class="divider-vertical"></li>
<li><a href="overview.html">Overview</a></li>
<li><a href="compatible_idioms.html">Cheat Sheet</a></li>
<li><a href="faq.html">FAQ</a></li>
<li class="dropdown globaltoc-container">
<a role="button"
id="dLabelGlobalToc"
data-toggle="dropdown"
data-target="#"
href="index.html">Contents <b class="caret"></b></a>
<ul class="dropdown-menu globaltoc"
role="menu"
aria-labelledby="dLabelGlobalToc"><ul>
<li class="toctree-l1"><a class="reference internal" href="whatsnew.html">What’s New</a><ul>
<li class="toctree-l2"><a class="reference internal" href="whatsnew.html#what-s-new-in-version-0-15-0-2015-07-25">What’s new in version 0.15.0 (2015-07-25)</a></li>
<li class="toctree-l2"><a class="reference internal" href="whatsnew.html#what-s-new-in-version-0-14-3-2014-12-15">What’s new in version 0.14.3 (2014-12-15)</a></li>
<li class="toctree-l2"><a class="reference internal" href="whatsnew.html#what-s-new-in-version-0-14-2-2014-11-21">What’s new in version 0.14.2 (2014-11-21)</a></li>
<li class="toctree-l2"><a class="reference internal" href="whatsnew.html#what-s-new-in-version-0-14-1-2014-10-02">What’s new in version 0.14.1 (2014-10-02)</a></li>
<li class="toctree-l2"><a class="reference internal" href="whatsnew.html#what-s-new-in-version-0-14-2014-10-02">What’s new in version 0.14 (2014-10-02)</a><ul>
<li class="toctree-l3"><a class="reference internal" href="whatsnew.html#bug-fixes">Bug fixes</a></li>
<li class="toctree-l3"><a class="reference internal" href="whatsnew.html#internal-cleanups">Internal cleanups</a></li>
<li class="toctree-l3"><a class="reference internal" href="whatsnew.html#deprecations">Deprecations</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="whatsnew.html#previous-versions">Previous versions</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="overview.html">Overview: Easy, clean, reliable Python 2/3 compatibility</a><ul>
<li class="toctree-l2"><a class="reference internal" href="overview.html#features">Features</a></li>
<li class="toctree-l2"><a class="reference internal" href="overview.html#code-examples">Code examples</a></li>
<li class="toctree-l2"><a class="reference internal" href="overview.html#automatic-conversion-to-py2-3-compatible-code">Automatic conversion to Py2/3-compatible code</a><ul>
<li class="toctree-l3"><a class="reference internal" href="overview.html#futurize-2-to-both">Futurize: 2 to both</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="overview.html#automatic-translation">Automatic translation</a></li>
<li class="toctree-l2"><a class="reference internal" href="overview.html#licensing">Licensing</a></li>
<li class="toctree-l2"><a class="reference internal" href="overview.html#next-steps">Next steps</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="quickstart.html">Quick-start guide</a><ul>
<li class="toctree-l2"><a class="reference internal" href="quickstart.html#installation">Installation</a></li>
<li class="toctree-l2"><a class="reference internal" href="quickstart.html#if-you-are-writing-code-from-scratch">If you are writing code from scratch</a></li>
<li class="toctree-l2"><a class="reference internal" href="quickstart.html#to-convert-existing-python-3-code">To convert existing Python 3 code</a></li>
<li class="toctree-l2"><a class="reference internal" href="quickstart.html#to-convert-existing-python-2-code">To convert existing Python 2 code</a></li>
<li class="toctree-l2"><a class="reference internal" href="quickstart.html#standard-library-reorganization">Standard library reorganization</a></li>
<li class="toctree-l2"><a class="reference internal" href="quickstart.html#python-2-only-dependencies">Python 2-only dependencies</a></li>
<li class="toctree-l2"><a class="reference internal" href="quickstart.html#next-steps">Next steps</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="compatible_idioms.html">Cheat Sheet: Writing Python 2-3 compatible code</a><ul>
<li class="toctree-l2"><a class="reference internal" href="compatible_idioms.html#setup">Setup</a></li>
<li class="toctree-l2"><a class="reference internal" href="compatible_idioms.html#essential-syntax-differences">Essential syntax differences</a><ul>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#print">print</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#raising-exceptions">Raising exceptions</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#catching-exceptions">Catching exceptions</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#division">Division</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#long-integers">Long integers</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#octal-constants">Octal constants</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#backtick-repr">Backtick repr</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#metaclasses">Metaclasses</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="compatible_idioms.html#strings-and-bytes">Strings and bytes</a><ul>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#unicode-text-string-literals">Unicode (text) string literals</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#byte-string-literals">Byte-string literals</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#basestring">basestring</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#unicode">unicode</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#stringio">StringIO</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="compatible_idioms.html#imports-relative-to-a-package">Imports relative to a package</a></li>
<li class="toctree-l2"><a class="reference internal" href="compatible_idioms.html#dictionaries">Dictionaries</a><ul>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#iterating-through-dict-keys-values-items">Iterating through <code class="docutils literal"><span class="pre">dict</span></code> keys/values/items</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#dict-keys-values-items-as-a-list">dict keys/values/items as a list</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="compatible_idioms.html#custom-class-behaviour">Custom class behaviour</a><ul>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#custom-iterators">Custom iterators</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#custom-str-methods">Custom <code class="docutils literal"><span class="pre">__str__</span></code> methods</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#custom-nonzero-vs-bool-method">Custom <code class="docutils literal"><span class="pre">__nonzero__</span></code> vs <code class="docutils literal"><span class="pre">__bool__</span></code> method:</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="compatible_idioms.html#lists-versus-iterators">Lists versus iterators</a><ul>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#xrange">xrange</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#range">range</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#map">map</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#imap">imap</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#zip-izip">zip, izip</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#filter-ifilter">filter, ifilter</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="compatible_idioms.html#other-builtins">Other builtins</a><ul>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#file-io-with-open">File IO with open()</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#reduce">reduce()</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#raw-input">raw_input()</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#input">input()</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#file">file()</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#execfile">execfile()</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#unichr">unichr()</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#intern">intern()</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#apply">apply()</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#chr">chr()</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#cmp">cmp()</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#reload">reload()</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="compatible_idioms.html#standard-library">Standard library</a><ul>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#dbm-modules">dbm modules</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#commands-subprocess-modules">commands / subprocess modules</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#subprocess-check-output">subprocess.check_output()</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#collections-counter-and-ordereddict">collections: Counter and OrderedDict</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#stringio-module">StringIO module</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#http-module">http module</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#xmlrpc-module">xmlrpc module</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#html-escaping-and-entities">html escaping and entities</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#html-parsing">html parsing</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#urllib-module">urllib module</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#tkinter">Tkinter</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#socketserver">socketserver</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#copy-reg-copyreg">copy_reg, copyreg</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#configparser">configparser</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#queue">queue</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#repr-reprlib">repr, reprlib</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#userdict-userlist-userstring">UserDict, UserList, UserString</a></li>
<li class="toctree-l3"><a class="reference internal" href="compatible_idioms.html#itertools-filterfalse-zip-longest">itertools: filterfalse, zip_longest</a></li>
</ul>
</li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="imports.html">Imports</a><ul>
<li class="toctree-l2"><a class="reference internal" href="imports.html#future-imports">__future__ imports</a></li>
<li class="toctree-l2"><a class="reference internal" href="imports.html#imports-of-builtins">Imports of builtins</a><ul>
<li class="toctree-l3"><a class="reference internal" href="imports.html#implicit-imports">Implicit imports</a></li>
<li class="toctree-l3"><a class="reference internal" href="imports.html#explicit-imports">Explicit imports</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="imports.html#standard-library-imports">Standard library imports</a><ul>
<li class="toctree-l3"><a class="reference internal" href="imports.html#direct-imports">Direct imports</a></li>
<li class="toctree-l3"><a class="reference internal" href="imports.html#aliased-imports">Aliased imports</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="imports.html#external-standard-library-backports">External standard-library backports</a></li>
<li class="toctree-l2"><a class="reference internal" href="imports.html#included-full-backports">Included full backports</a></li>
<li class="toctree-l2"><a class="reference internal" href="imports.html#using-python-2-only-dependencies-on-python-3">Using Python 2-only dependencies on Python 3</a></li>
<li class="toctree-l2"><a class="reference internal" href="imports.html#should-i-import-unicode-literals">Should I import unicode_literals?</a><ul>
<li class="toctree-l3"><a class="reference internal" href="imports.html#benefits">Benefits</a></li>
<li class="toctree-l3"><a class="reference internal" href="imports.html#drawbacks">Drawbacks</a></li>
<li class="toctree-l3"><a class="reference internal" href="imports.html#others-perspectives">Others’ perspectives</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="imports.html#next-steps">Next steps</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="what_else.html">What else you need to know</a><ul>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#bytes">bytes</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#str">str</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#dict">dict</a><ul>
<li class="toctree-l3"><a class="reference internal" href="what_else.html#memory-efficiency-and-alternatives">Memory-efficiency and alternatives</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#int">int</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#isinstance">isinstance</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#passing-data-to-from-python-2-libraries">Passing data to/from Python 2 libraries</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#native-string-type">Native string type</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#open">open()</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#custom-str-methods">Custom __str__ methods</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#custom-iterators">Custom iterators</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#binding-a-method-to-a-class">Binding a method to a class</a></li>
<li class="toctree-l2"><a class="reference internal" href="what_else.html#metaclasses">Metaclasses</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="automatic_conversion.html">Automatic conversion to Py2/3</a><ul>
<li class="toctree-l2"><a class="reference internal" href="automatic_conversion.html#futurize-py2-to-py2-3"><code class="docutils literal"><span class="pre">futurize</span></code>: Py2 to Py2/3</a><ul>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#stage-1-safe-fixes">Stage 1: “safe” fixes</a></li>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#stage-2-py3-style-code-with-wrappers-for-py2">Stage 2: Py3-style code with wrappers for Py2</a></li>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#separating-text-from-bytes">Separating text from bytes</a></li>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#post-conversion">Post-conversion</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="automatic_conversion.html#futurize-quick-start-guide"><code class="docutils literal"><span class="pre">futurize</span></code> quick-start guide</a><ul>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#step-0-setup">Step 0: setup</a></li>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#step-1-modern-py2-code">Step 1: modern Py2 code</a></li>
<li class="toctree-l3"><a class="reference internal" href="automatic_conversion.html#step-2-working-py3-code-that-still-supports-py2">Step 2: working Py3 code that still supports Py2</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="automatic_conversion.html#pasteurize-py3-to-py2-3"><code class="docutils literal"><span class="pre">pasteurize</span></code>: Py3 to Py2/3</a></li>
<li class="toctree-l2"><a class="reference internal" href="automatic_conversion.html#known-limitations">Known limitations</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="faq.html">Frequently Asked Questions (FAQ)</a><ul>
<li class="toctree-l2"><a class="reference internal" href="faq.html#who-is-this-for">Who is this for?</a></li>
<li class="toctree-l2"><a class="reference internal" href="faq.html#why-upgrade-to-python-3">Why upgrade to Python 3?</a></li>
<li class="toctree-l2"><a class="reference internal" href="faq.html#porting-philosophy">Porting philosophy</a><ul>
<li class="toctree-l3"><a class="reference internal" href="faq.html#why-write-python-3-style-code">Why write Python 3-style code?</a></li>
<li class="toctree-l3"><a class="reference internal" href="faq.html#can-t-i-just-roll-my-own-py2-3-compatibility-layer">Can’t I just roll my own Py2/3 compatibility layer?</a></li>
<li class="toctree-l3"><a class="reference internal" href="faq.html#what-inspired-this-project">What inspired this project?</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="faq.html#maturity">Maturity</a><ul>
<li class="toctree-l3"><a class="reference internal" href="faq.html#how-well-has-it-been-tested">How well has it been tested?</a></li>
<li class="toctree-l3"><a class="reference internal" href="faq.html#is-the-api-stable">Is the API stable?</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="faq.html#relationship-between-python-future-and-other-compatibility-tools">Relationship between python-future and other compatibility tools</a><ul>
<li class="toctree-l3"><a class="reference internal" href="faq.html#how-does-this-relate-to-2to3">How does this relate to <code class="docutils literal"><span class="pre">2to3</span></code>?</a></li>
<li class="toctree-l3"><a class="reference internal" href="faq.html#can-i-maintain-a-python-2-codebase-and-use-2to3-to-automatically-convert-to-python-3-in-the-setup-script">Can I maintain a Python 2 codebase and use 2to3 to automatically convert to Python 3 in the setup script?</a></li>
<li class="toctree-l3"><a class="reference internal" href="faq.html#what-is-the-relationship-between-future-and-six">What is the relationship between <code class="docutils literal"><span class="pre">future</span></code> and <code class="docutils literal"><span class="pre">six</span></code>?</a></li>
<li class="toctree-l3"><a class="reference internal" href="faq.html#what-is-the-relationship-between-python-future-and-python-modernize">What is the relationship between <code class="docutils literal"><span class="pre">python-future</span></code> and <code class="docutils literal"><span class="pre">python-modernize</span></code>?</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="faq.html#platform-and-version-support">Platform and version support</a><ul>
<li class="toctree-l3"><a class="reference internal" href="faq.html#which-versions-of-python-does-python-future-support">Which versions of Python does <code class="docutils literal"><span class="pre">python-future</span></code> support?</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="faq.html#support">Support</a><ul>
<li class="toctree-l3"><a class="reference internal" href="faq.html#is-there-a-mailing-list">Is there a mailing list?</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="faq.html#contributing">Contributing</a><ul>
<li class="toctree-l3"><a class="reference internal" href="faq.html#can-i-help">Can I help?</a></li>
<li class="toctree-l3"><a class="reference internal" href="faq.html#where-is-the-repo">Where is the repo?</a></li>
</ul>
</li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="stdlib_incompatibilities.html">Standard library incompatibilities</a><ul>
<li class="toctree-l2"><a class="reference internal" href="stdlib_incompatibilities.html#array-array">array.array()</a></li>
<li class="toctree-l2"><a class="reference internal" href="stdlib_incompatibilities.html#array-array-read">array.array.read()</a></li>
<li class="toctree-l2"><a class="reference internal" href="stdlib_incompatibilities.html#base64-decodebytes-and-base64-encodebytes">base64.decodebytes() and base64.encodebytes()</a></li>
<li class="toctree-l2"><a class="reference internal" href="stdlib_incompatibilities.html#re-ascii">re.ASCII</a></li>
<li class="toctree-l2"><a class="reference internal" href="stdlib_incompatibilities.html#struct-pack">struct.pack()</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="older_interfaces.html">Older interfaces</a><ul>
<li class="toctree-l2"><a class="reference internal" href="older_interfaces.html#context-manager-for-import-hooks">Context-manager for import hooks</a></li>
<li class="toctree-l2"><a class="reference internal" href="older_interfaces.html#future-moves-interface"><code class="docutils literal"><span class="pre">future.moves</span></code> interface</a><ul>
<li class="toctree-l3"><a class="reference internal" href="older_interfaces.html#comparing-future-moves-and-six-moves">Comparing future.moves and six.moves</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="older_interfaces.html#import-and-from-import-functions"><code class="docutils literal"><span class="pre">import_</span></code> and <code class="docutils literal"><span class="pre">from_import</span></code> functions</a></li>
<li class="toctree-l2"><a class="reference internal" href="older_interfaces.html#install-hooks-call">install_hooks() call</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="changelog.html">Changes in previous versions</a><ul>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-13-1-2014-09-23">Changes in version 0.13.1 (2014-09-23)</a></li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-13-2014-08-13">Changes in version 0.13 (2014-08-13)</a><ul>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#deprecations">Deprecations</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#new-features">New features</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#bug-fixes">Bug fixes</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-12-4-2014-07-18">Changes in version 0.12.4 (2014-07-18)</a></li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-12-3-2014-06-19">Changes in version 0.12.3 (2014-06-19)</a></li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-12-2-2014-05-25">Changes in version 0.12.2 (2014-05-25)</a></li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-12-1-2014-05-14">Changes in version 0.12.1 (2014-05-14)</a></li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-12-0-2014-05-06">Changes in version 0.12.0 (2014-05-06)</a><ul>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#more-robust-standard-library-import-hooks">More robust standard-library import hooks</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#newobject-base-object-defines-fallback-py2-compatible-special-methods"><code class="docutils literal"><span class="pre">newobject</span></code> base object defines fallback Py2-compatible special methods</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#past-builtins-module-improved"><code class="docutils literal"><span class="pre">past.builtins</span></code> module improved</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#surrogateescape-error-handler"><code class="docutils literal"><span class="pre">surrogateescape</span></code> error handler</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#newlist-type"><code class="docutils literal"><span class="pre">newlist</span></code> type</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#listvalues-and-listitems"><code class="docutils literal"><span class="pre">listvalues</span></code> and <code class="docutils literal"><span class="pre">listitems</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#tests">Tests</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#refactoring-of-future-standard-library-future-backports">Refactoring of <code class="docutils literal"><span class="pre">future.standard_library.*</span></code> -> <code class="docutils literal"><span class="pre">future.backports</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#backported-http-server-and-urllib-modules">Backported <code class="docutils literal"><span class="pre">http.server</span></code> and <code class="docutils literal"><span class="pre">urllib</span></code> modules</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#internal-refactoring">Internal refactoring</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#id1">Bug fixes</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-11-4-2014-05-25">Changes in version 0.11.4 (2014-05-25)</a></li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-11-3-2014-02-27">Changes in version 0.11.3 (2014-02-27)</a><ul>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#improved-compatibility-with-requests">Improved compatibility with <code class="docutils literal"><span class="pre">requests</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#conversion-scripts-explicitly-install-import-hooks">Conversion scripts explicitly install import hooks</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#futurize-script-no-longer-adds-unicode-literals-by-default"><code class="docutils literal"><span class="pre">futurize</span></code> script no longer adds <code class="docutils literal"><span class="pre">unicode_literals</span></code> by default</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-11-2014-01-28">Changes in version 0.11 (2014-01-28)</a><ul>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#past-package"><code class="docutils literal"><span class="pre">past</span></code> package</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#auto-translation-of-python-2-modules-upon-import">Auto-translation of Python 2 modules upon import</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#separate-pasteurize-script">Separate <code class="docutils literal"><span class="pre">pasteurize</span></code> script</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#pow">pow()</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#input-no-longer-disabled-globally-on-py2">input() no longer disabled globally on Py2</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#deprecated-feature-auto-installation-of-standard-library-import-hooks">Deprecated feature: auto-installation of standard-library import hooks</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#internal-changes">Internal changes</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-10-2-2014-01-11">Changes in version 0.10.2 (2014-01-11)</a><ul>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#new-context-manager-interface-to-standard-library-hooks">New context-manager interface to standard_library hooks</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-10-0-2013-12-02">Changes in version 0.10.0 (2013-12-02)</a><ul>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#backported-dict-type">Backported <code class="docutils literal"><span class="pre">dict</span></code> type</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#utility-functions-raise-and-exec">Utility functions <code class="docutils literal"><span class="pre">raise_</span></code> and <code class="docutils literal"><span class="pre">exec_</span></code></a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#bugfixes">Bugfixes</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-9-2013-11-06">Changes in version 0.9 (2013-11-06)</a><ul>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#isinstance-checks-are-supported-natively-with-backported-types"><code class="docutils literal"><span class="pre">isinstance</span></code> checks are supported natively with backported types</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#futurize-minimal-imports-by-default"><code class="docutils literal"><span class="pre">futurize</span></code>: minimal imports by default</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#looser-type-checking-for-the-backported-str-object">Looser type-checking for the backported <code class="docutils literal"><span class="pre">str</span></code> object</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#suspend-hooks-context-manager-added-to-future-standard-library">suspend_hooks() context manager added to <code class="docutils literal"><span class="pre">future.standard_library</span></code></a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#changes-in-version-0-8-2013-10-28">Changes in version 0.8 (2013-10-28)</a><ul>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#python-2-6-support">Python 2.6 support</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#unused-modules-removed">Unused modules removed</a></li>
<li class="toctree-l3"><a class="reference internal" href="changelog.html#isinstance-added-to-future-builtins-v0-8-2">isinstance() added to <code class="docutils literal"><span class="pre">future.builtins</span></code> (v0.8.2)</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="changelog.html#summary-of-all-changes">Summary of all changes</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="credits.html">Licensing and credits</a><ul>
<li class="toctree-l2"><a class="reference internal" href="credits.html#licence">Licence</a></li>
<li class="toctree-l2"><a class="reference internal" href="credits.html#sponsor">Sponsor</a></li>
<li class="toctree-l2"><a class="reference internal" href="credits.html#authors">Authors</a><ul>
<li class="toctree-l3"><a class="reference internal" href="credits.html#development-lead">Development Lead</a></li>
<li class="toctree-l3"><a class="reference internal" href="credits.html#patches">Patches</a></li>
<li class="toctree-l3"><a class="reference internal" href="credits.html#suggestions-and-feedback">Suggestions and Feedback</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="credits.html#other-credits">Other Credits</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="reference.html">API Reference (in progress)</a><ul>
<li class="toctree-l2"><a class="reference internal" href="reference.html#module-future.builtins">future.builtins Interface</a></li>
<li class="toctree-l2"><a class="reference internal" href="reference.html#module-future.types">Backported types from Python 3</a><ul>
<li class="toctree-l3"><a class="reference internal" href="reference.html#for-more-information">For more information:</a></li>
<li class="toctree-l3"><a class="reference internal" href="reference.html#range">range()</a></li>
<li class="toctree-l3"><a class="reference internal" href="reference.html#super">super()</a></li>
<li class="toctree-l3"><a class="reference internal" href="reference.html#round">round()</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="reference.html#module-future.standard_library">future.standard_library Interface</a><ul>
<li class="toctree-l3"><a class="reference internal" href="reference.html#limitations">Limitations</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="reference.html#module-future.utils">future.utils Interface</a></li>
<li class="toctree-l2"><a class="reference internal" href="reference.html#module-past.builtins">past.builtins Interface</a></li>
<li class="toctree-l2"><a class="reference internal" href="reference.html#module-past.types">Forward-ported types from Python 2</a></li>
</ul>
</li>
</ul>
</ul>
</li>
<li class="dropdown">
<a role="button"
id="dLabelLocalToc"
data-toggle="dropdown"
data-target="#"
href="#">Page <b class="caret"></b></a>
<ul class="dropdown-menu localtoc"
role="menu"
aria-labelledby="dLabelLocalToc"><ul>
<li><a class="reference internal" href="#"><code class="docutils literal"><span class="pre">futurize</span></code>: Py2 to Py2/3</a><ul>
<li><a class="reference internal" href="#stage-1-safe-fixes">Stage 1: “safe” fixes</a></li>
<li><a class="reference internal" href="#stage-2-py3-style-code-with-wrappers-for-py2">Stage 2: Py3-style code with wrappers for Py2</a></li>
<li><a class="reference internal" href="#separating-text-from-bytes">Separating text from bytes</a></li>
<li><a class="reference internal" href="#post-conversion">Post-conversion</a></li>
</ul>
</li>
</ul>
</ul>
</li>
</ul>
<form class="navbar-form navbar-right" action="search.html" method="get">
<div class="form-group">
<input type="text" name="q" class="form-control" placeholder="Search" />
</div>
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
</div>
</div>
</div>
<div class="container">
<div class="row">
<div class="col-md-3">
<div id="sidebar" class="bs-sidenav" role="complementary"><!--<h3>Python-Future</h3>
<p>-->
<h4>Easy, clean, reliable Python 2/3 compatibility</h4>
<a href="http://python-future.org">Table of Contents</a>
<!--
</p>
<h3>Other Formats</h3>
<p>
You can download the documentation in other formats as well:
</p>
<ul>
<li><a href="http://jinja.pocoo.org/docs/jinja-docs.pdf">as PDF</a>
<li><a href="http://jinja.pocoo.org/docs/jinja-docs.zip">as zipped HTML</a>
</ul>
-->
<!--<h3>Useful Links</h3>
<ul>
<li><a href="http://pypi.python.org/pypi/future">on PyPI</a></li>
<li><a href="https://github.com/PythonCharmers/python-future">on GitHub</a></li>
</ul>
--><ul>
<li class="toctree-l1"><a class="reference internal" href="whatsnew.html">What’s New</a></li>
<li class="toctree-l1"><a class="reference internal" href="overview.html">Overview: Easy, clean, reliable Python 2/3 compatibility</a></li>
<li class="toctree-l1"><a class="reference internal" href="quickstart.html">Quick-start guide</a></li>
<li class="toctree-l1"><a class="reference internal" href="compatible_idioms.html">Cheat Sheet: Writing Python 2-3 compatible code</a></li>
<li class="toctree-l1"><a class="reference internal" href="imports.html">Imports</a></li>
<li class="toctree-l1"><a class="reference internal" href="what_else.html">What else you need to know</a></li>
<li class="toctree-l1"><a class="reference internal" href="automatic_conversion.html">Automatic conversion to Py2/3</a></li>
<li class="toctree-l1"><a class="reference internal" href="faq.html">Frequently Asked Questions (FAQ)</a></li>
<li class="toctree-l1"><a class="reference internal" href="stdlib_incompatibilities.html">Standard library incompatibilities</a></li>
<li class="toctree-l1"><a class="reference internal" href="older_interfaces.html">Older interfaces</a></li>
<li class="toctree-l1"><a class="reference internal" href="changelog.html">Changes in previous versions</a></li>
<li class="toctree-l1"><a class="reference internal" href="credits.html">Licensing and credits</a></li>
<li class="toctree-l1"><a class="reference internal" href="reference.html">API Reference (in progress)</a></li>
</ul>
</div>
</div>
<div class="col-md-9">
<div class="section" id="futurize-py2-to-py2-3">
<span id="forwards-conversion"></span><h1><code class="docutils literal"><span class="pre">futurize</span></code>: Py2 to Py2/3<a class="headerlink" href="#futurize-py2-to-py2-3" title="Permalink to this headline">¶</a></h1>
<p>The <code class="docutils literal"><span class="pre">futurize</span></code> script passes Python 2 code through all the appropriate fixers
to turn it into valid Python 3 code, and then adds <code class="docutils literal"><span class="pre">__future__</span></code> and
<code class="docutils literal"><span class="pre">future</span></code> package imports to re-enable compatibility with Python 2.</p>
<p>For example, running <code class="docutils literal"><span class="pre">futurize</span></code> turns this Python 2 code:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">ConfigParser</span> <span class="c"># Py2 module name</span>
<span class="k">class</span> <span class="nc">Upper</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">iterable</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_iter</span> <span class="o">=</span> <span class="nb">iter</span><span class="p">(</span><span class="n">iterable</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">next</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="c"># Py2-style iterator interface</span>
<span class="k">return</span> <span class="nb">next</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">_iter</span><span class="p">)</span><span class="o">.</span><span class="n">upper</span><span class="p">()</span>
<span class="k">def</span> <span class="nf">__iter__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span>
<span class="n">itr</span> <span class="o">=</span> <span class="n">Upper</span><span class="p">(</span><span class="s">'hello'</span><span class="p">)</span>
<span class="k">print</span> <span class="nb">next</span><span class="p">(</span><span class="n">itr</span><span class="p">),</span>
<span class="k">for</span> <span class="n">letter</span> <span class="ow">in</span> <span class="n">itr</span><span class="p">:</span>
<span class="k">print</span> <span class="n">letter</span><span class="p">,</span> <span class="c"># Py2-style print statement</span>
</pre></div>
</div>
<p>into this code which runs on both Py2 and Py3:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">__future__</span> <span class="kn">import</span> <span class="n">print_function</span>
<span class="kn">from</span> <span class="nn">future</span> <span class="kn">import</span> <span class="n">standard_library</span>
<span class="n">standard_library</span><span class="o">.</span><span class="n">install_aliases</span><span class="p">()</span>
<span class="kn">from</span> <span class="nn">future.builtins</span> <span class="kn">import</span> <span class="nb">next</span>
<span class="kn">from</span> <span class="nn">future.builtins</span> <span class="kn">import</span> <span class="nb">object</span>
<span class="kn">import</span> <span class="nn">configparser</span> <span class="c"># Py3-style import</span>
<span class="k">class</span> <span class="nc">Upper</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">iterable</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">_iter</span> <span class="o">=</span> <span class="nb">iter</span><span class="p">(</span><span class="n">iterable</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">__next__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span> <span class="c"># Py3-style iterator interface</span>
<span class="k">return</span> <span class="nb">next</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">_iter</span><span class="p">)</span><span class="o">.</span><span class="n">upper</span><span class="p">()</span>
<span class="k">def</span> <span class="nf">__iter__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span>
<span class="n">itr</span> <span class="o">=</span> <span class="n">Upper</span><span class="p">(</span><span class="s">'hello'</span><span class="p">)</span>
<span class="k">print</span><span class="p">(</span><span class="nb">next</span><span class="p">(</span><span class="n">itr</span><span class="p">),</span> <span class="n">end</span><span class="o">=</span><span class="s">' '</span><span class="p">)</span> <span class="c"># Py3-style print function</span>
<span class="k">for</span> <span class="n">letter</span> <span class="ow">in</span> <span class="n">itr</span><span class="p">:</span>
<span class="k">print</span><span class="p">(</span><span class="n">letter</span><span class="p">,</span> <span class="n">end</span><span class="o">=</span><span class="s">' '</span><span class="p">)</span>
</pre></div>
</div>
<p>To write out all the changes to your Python files that <code class="docutils literal"><span class="pre">futurize</span></code> suggests,
use the <code class="docutils literal"><span class="pre">-w</span></code> flag.</p>
<p>For complex projects, it is probably best to divide the porting into two stages.
Stage 1 is for “safe” changes that modernize the code but do not break Python
2.6 compatibility or introduce a depdendency on the <code class="docutils literal"><span class="pre">future</span></code> package. Stage 2
is to complete the process.</p>
<div class="section" id="stage-1-safe-fixes">
<span id="forwards-conversion-stage1"></span><h2>Stage 1: “safe” fixes<a class="headerlink" href="#stage-1-safe-fixes" title="Permalink to this headline">¶</a></h2>
<p>Run the first stage of the conversion process with:</p>
<div class="highlight-python"><div class="highlight"><pre>futurize --stage1 mypackage/*.py
</pre></div>
</div>
<p>or, if you are using zsh, recursively:</p>
<div class="highlight-python"><div class="highlight"><pre>futurize --stage1 mypackage/**/*.py
</pre></div>
</div>
<p>This applies fixes that modernize Python 2 code without changing the effect of
the code. With luck, this will not introduce any bugs into the code, or will at
least be trivial to fix. The changes are those that bring the Python code
up-to-date without breaking Py2 compatibility. The resulting code will be
modern Python 2.6-compatible code plus <code class="docutils literal"><span class="pre">__future__</span></code> imports from the
following set:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">__future__</span> <span class="kn">import</span> <span class="n">absolute_import</span>
<span class="kn">from</span> <span class="nn">__future__</span> <span class="kn">import</span> <span class="n">division</span>
<span class="kn">from</span> <span class="nn">__future__</span> <span class="kn">import</span> <span class="n">print_function</span>
</pre></div>
</div>
<p>Only those <code class="docutils literal"><span class="pre">__future__</span></code> imports deemed necessary will be added unless
the <code class="docutils literal"><span class="pre">--all-imports</span></code> command-line option is passed to <code class="docutils literal"><span class="pre">futurize</span></code>, in
which case they are all added.</p>
<p>The <code class="docutils literal"><span class="pre">from</span> <span class="pre">__future__</span> <span class="pre">import</span> <span class="pre">unicode_literals</span></code> declaration is not added
unless the <code class="docutils literal"><span class="pre">--unicode-literals</span></code> flag is passed to <code class="docutils literal"><span class="pre">futurize</span></code>.</p>
<p>The changes include:</p>
<div class="highlight-python"><div class="highlight"><pre>- except MyException, e:
+ except MyException as e:
- print >>stderr, "Blah"
+ from __future__ import print_function
+ print("Blah", stderr)
- class MyClass:
+ class MyClass(object):
- def next(self):
+ def __next__(self):
- if d.has_key(key):
+ if key in d:
</pre></div>
</div>
<p>Implicit relative imports fixed, e.g.:</p>
<div class="highlight-python"><div class="highlight"><pre>- import mymodule
+ from __future__ import absolute_import
+ from . import mymodule
</pre></div>
</div>
<p>Stage 1 does not add any imports from the <code class="docutils literal"><span class="pre">future</span></code> package. The output of
stage 1 will probably not (yet) run on Python 3.</p>
<p>The goal for this stage is to create most of the <code class="docutils literal"><span class="pre">diff</span></code> for the entire
porting process, but without introducing any bugs. It should be uncontroversial
and safe to apply to every Python 2 package. The subsequent patches introducing
Python 3 compatibility should then be shorter and easier to review.</p>
<p>The complete set of fixers applied by <code class="docutils literal"><span class="pre">futurize</span> <span class="pre">--stage1</span></code> is:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_apply</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_except</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_exitfunc</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_funcattrs</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_has_key</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_idioms</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_intern</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_isinstance</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_methodattrs</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_ne</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_numliterals</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_paren</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_reduce</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_renames</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_repr</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_standarderror</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_sys_exc</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_throw</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_tuple_params</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_types</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_ws_comma</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_xreadlines</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_absolute_import</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_next_call</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_print_with_import</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_raise</span>
</pre></div>
</div>
<p>The following fixers from <code class="docutils literal"><span class="pre">lib2to3</span></code> are not applied:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_import</span>
</pre></div>
</div>
<p>The <code class="docutils literal"><span class="pre">fix_absolute_import</span></code> fixer in <code class="docutils literal"><span class="pre">libfuturize.fixes</span></code> is applied instead of
<code class="docutils literal"><span class="pre">lib2to3.fixes.fix_import</span></code>. The new fixer both makes implicit relative
imports explicit and adds the declaration <code class="docutils literal"><span class="pre">from</span> <span class="pre">__future__</span> <span class="pre">import</span>
<span class="pre">absolute_import</span></code> at the top of each relevant module.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_next</span>
</pre></div>
</div>
<p>The <code class="docutils literal"><span class="pre">fix_next_call</span></code> fixer in <code class="docutils literal"><span class="pre">libfuturize.fixes</span></code> is applied instead of
<code class="docutils literal"><span class="pre">fix_next</span></code> in stage 1. The new fixer changes any <code class="docutils literal"><span class="pre">obj.next()</span></code> calls to
<code class="docutils literal"><span class="pre">next(obj)</span></code>, which is Py2/3 compatible, but doesn’t change any <code class="docutils literal"><span class="pre">next</span></code> method
names to <code class="docutils literal"><span class="pre">__next__</span></code>, which would break Py2 compatibility.</p>
<p><code class="docutils literal"><span class="pre">fix_next</span></code> is applied in stage 2.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_print</span>
</pre></div>
</div>
<p>The <code class="docutils literal"><span class="pre">fix_print_with_import</span></code> fixer in <code class="docutils literal"><span class="pre">libfuturize.fixes</span></code> changes the code to
use print as a function and also adds <code class="docutils literal"><span class="pre">from</span> <span class="pre">__future__</span> <span class="pre">import</span>
<span class="pre">print_function</span></code> to the top of modules using <code class="docutils literal"><span class="pre">print()</span></code>.</p>
<p>In addition, it avoids adding an extra set of parentheses if these already
exist. So <code class="docutils literal"><span class="pre">print(x)</span></code> does not become <code class="docutils literal"><span class="pre">print((x))</span></code>.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_raise</span>
</pre></div>
</div>
<p>This fixer translates code to use the Python 3-only <code class="docutils literal"><span class="pre">with_traceback()</span></code>
method on exceptions.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_set_literal</span>
</pre></div>
</div>
<p>This converts <code class="docutils literal"><span class="pre">set([1,</span> <span class="pre">2,</span> <span class="pre">3]</span></code>) to <code class="docutils literal"><span class="pre">{1,</span> <span class="pre">2,</span> <span class="pre">3}</span></code>, breaking Python 2.6 support.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_ws_comma</span>
</pre></div>
</div>
<p>This performs cosmetic changes. This is not applied by default because it
does not serve to improve Python 2/3 compatibility. (In some cases it may
also reduce readability: see issue #58.)</p>
</div>
<div class="section" id="stage-2-py3-style-code-with-wrappers-for-py2">
<span id="forwards-conversion-stage2"></span><h2>Stage 2: Py3-style code with wrappers for Py2<a class="headerlink" href="#stage-2-py3-style-code-with-wrappers-for-py2" title="Permalink to this headline">¶</a></h2>
<p>Run stage 2 of the conversion process with:</p>
<div class="highlight-python"><div class="highlight"><pre>futurize --stage2 myfolder/*.py
</pre></div>
</div>
<p>This stage adds a dependency on the <code class="docutils literal"><span class="pre">future</span></code> package. The goal for stage 2 is
to make further mostly safe changes to the Python 2 code to use Python 3-style
code that then still runs on Python 2 with the help of the appropriate builtins
and utilities in <code class="docutils literal"><span class="pre">future</span></code>.</p>
<p>For example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">name</span> <span class="o">=</span> <span class="nb">raw_input</span><span class="p">(</span><span class="s">'What is your name?</span><span class="se">\n</span><span class="s">'</span><span class="p">)</span>
<span class="k">for</span> <span class="n">k</span><span class="p">,</span> <span class="n">v</span> <span class="ow">in</span> <span class="n">d</span><span class="o">.</span><span class="n">iteritems</span><span class="p">():</span>
<span class="k">assert</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">v</span><span class="p">,</span> <span class="nb">basestring</span><span class="p">)</span>
<span class="k">class</span> <span class="nc">MyClass</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">__unicode__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="s">u'My object'</span>
<span class="k">def</span> <span class="nf">__str__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="nb">unicode</span><span class="p">(</span><span class="bp">self</span><span class="p">)</span><span class="o">.</span><span class="n">encode</span><span class="p">(</span><span class="s">'utf-8'</span><span class="p">)</span>
</pre></div>
</div>
<p>would be converted by Stage 2 to this code:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">builtins</span> <span class="kn">import</span> <span class="nb">input</span>
<span class="kn">from</span> <span class="nn">builtins</span> <span class="kn">import</span> <span class="nb">str</span>
<span class="kn">from</span> <span class="nn">future.utils</span> <span class="kn">import</span> <span class="n">iteritems</span><span class="p">,</span> <span class="n">python_2_unicode_compatible</span>
<span class="n">name</span> <span class="o">=</span> <span class="nb">input</span><span class="p">(</span><span class="s">'What is your name?</span><span class="se">\n</span><span class="s">'</span><span class="p">)</span>
<span class="k">for</span> <span class="n">k</span><span class="p">,</span> <span class="n">v</span> <span class="ow">in</span> <span class="n">iteritems</span><span class="p">(</span><span class="n">d</span><span class="p">):</span>
<span class="k">assert</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">v</span><span class="p">,</span> <span class="p">(</span><span class="nb">str</span><span class="p">,</span> <span class="nb">bytes</span><span class="p">))</span>
<span class="nd">@python_2_unicode_compatible</span>
<span class="k">class</span> <span class="nc">MyClass</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">__str__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="s">u'My object'</span>
</pre></div>
</div>
<p>Stage 2 also renames standard-library imports to their Py3 names and adds these
two lines:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">future</span> <span class="kn">import</span> <span class="n">standard_library</span>
<span class="n">standard_library</span><span class="o">.</span><span class="n">install_aliases</span><span class="p">()</span>
</pre></div>
</div>
<p>For example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">ConfigParser</span>
</pre></div>
</div>
<p>becomes:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">future</span> <span class="kn">import</span> <span class="n">standard_library</span>
<span class="n">standard_library</span><span class="o">.</span><span class="n">install_aliases</span><span class="p">()</span>
<span class="kn">import</span> <span class="nn">configparser</span>
</pre></div>
</div>
<p>The complete list of fixers applied in Stage 2 is:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_basestring</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_dict</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_exec</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_getcwdu</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_input</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_itertools</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_itertools_imports</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_filter</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_long</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_map</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_nonzero</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_operator</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_raw_input</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_zip</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_cmp</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_division</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_execfile</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_future_builtins</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_future_standard_library</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_future_standard_library_urllib</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_metaclass</span>
<span class="n">libpasteurize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_newstyle</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_object</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_unicode_keep_u</span>
<span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_xrange_with_import</span>
</pre></div>
</div>
<p>Not applied:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_buffer</span> <span class="c"># Perhaps not safe. Test this.</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_callable</span> <span class="c"># Not needed in Py3.2+</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_execfile</span> <span class="c"># Some problems: see issue #37.</span>
<span class="c"># We use the custom libfuturize.fixes.fix_execfile instead.</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_future</span> <span class="c"># Removing __future__ imports is bad for Py2 compatibility!</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_imports</span> <span class="c"># Called by libfuturize.fixes.fix_future_standard_library</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_imports2</span> <span class="c"># We don't handle this yet (dbm)</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_metaclass</span> <span class="c"># Causes SyntaxError in Py2! Use the one from ``six`` instead</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_unicode</span> <span class="c"># Strips off the u'' prefix, which removes a potentially</span>
<span class="c"># helpful source of information for disambiguating</span>
<span class="c"># unicode/byte strings.</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_urllib</span> <span class="c"># Included in libfuturize.fix_future_standard_library_urllib</span>
<span class="n">lib2to3</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_xrange</span> <span class="c"># Custom one because of a bug with Py3.3's lib2to3</span>
</pre></div>
</div>
<p>Fixes applied with the <code class="docutils literal"><span class="pre">futurize</span> <span class="pre">--conservative</span></code> option:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="n">libfuturize</span><span class="o">.</span><span class="n">fixes</span><span class="o">.</span><span class="n">fix_division_safe</span> <span class="c"># instead of libfuturize.fixes.fix_division.</span>
</pre></div>
</div>
</div>
<div class="section" id="separating-text-from-bytes">
<span id="forwards-conversion-text"></span><h2>Separating text from bytes<a class="headerlink" href="#separating-text-from-bytes" title="Permalink to this headline">¶</a></h2>
<p>After applying stage 2, the recommended step is to decide which of your Python
2 strings represent text and which represent binary data and to prefix all
string literals with either <code class="docutils literal"><span class="pre">b</span></code> or <code class="docutils literal"><span class="pre">u</span></code> accordingly. Furthermore, to ensure
that these types behave similarly on Python 2 as on Python 3, also wrap
byte-strings or text in the <code class="docutils literal"><span class="pre">bytes</span></code> and <code class="docutils literal"><span class="pre">str</span></code> types from <code class="docutils literal"><span class="pre">future</span></code>. For
example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">from</span> <span class="nn">builtins</span> <span class="kn">import</span> <span class="nb">bytes</span><span class="p">,</span> <span class="nb">str</span>
<span class="n">b</span> <span class="o">=</span> <span class="nb">bytes</span><span class="p">(</span><span class="n">b</span><span class="s">'</span><span class="se">\x00</span><span class="s">ABCD'</span><span class="p">)</span>
<span class="n">s</span> <span class="o">=</span> <span class="nb">str</span><span class="p">(</span><span class="s">u'This is normal text'</span><span class="p">)</span>
</pre></div>
</div>
<p>Any unadorned string literals will then represent native platform strings
(byte-strings on Py2, unicode strings on Py3).</p>
<p>An alternative is to pass the <code class="docutils literal"><span class="pre">--unicode-literals</span></code> flag:</p>
<div class="highlight-python"><div class="highlight"><pre>$ futurize --unicode-literals mypython2script.py
</pre></div>
</div>
<p>After running this, all string literals that were not explicitly marked up as
<code class="docutils literal"><span class="pre">b''</span></code> will mean text (Python 3 <code class="docutils literal"><span class="pre">str</span></code> or Python 2 <code class="docutils literal"><span class="pre">unicode</span></code>).</p>
</div>
<div class="section" id="post-conversion">
<span id="forwards-conversion-stage3"></span><h2>Post-conversion<a class="headerlink" href="#post-conversion" title="Permalink to this headline">¶</a></h2>
<p>After running <code class="docutils literal"><span class="pre">futurize</span></code>, we recommend first running your tests on Python 3 and making further code changes until they pass on Python 3.</p>
<p>The next step would be manually tweaking the code to re-enable Python 2
compatibility with the help of the <code class="docutils literal"><span class="pre">future</span></code> package. For example, you can add
the <code class="docutils literal"><span class="pre">@python_2_unicode_compatible</span></code> decorator to any classes that define custom
<code class="docutils literal"><span class="pre">__str__</span></code> methods. See <a class="reference internal" href="what_else.html#what-else"><span>What else you need to know</span></a> for more info.</p>
</div>
</div>
</div>
</div>
</div>
<footer class="footer">
<div class="container">
<p class="pull-right">
<a href="#">Back to top</a>
</p>
<p>
© Copyright 2013-2015, Python Charmers Pty Ltd, Australia.<br/>
</p>
</div>
</footer>
<div class="footer">
<script type="text/javascript">
(function() {
var ga = document.createElement('script');
ga.src = ('https:' == document.location.protocol ?
'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
ga.setAttribute('async', 'true');
document.documentElement.firstChild.appendChild(ga);
})();
</script>
</div>
</body>
</html>
|
