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
|
# coding=utf-8
"""
past: compatibility with Python 2 from Python 3
===============================================
``past`` is a package to aid with Python 2/3 compatibility. Whereas ``future``
contains backports of Python 3 constructs to Python 2, ``past`` provides
implementations of some Python 2 constructs in Python 3 and tools to import and
run Python 2 code in Python 3. It is intended to be used sparingly, as a way of
running old Python 2 code from Python 3 until the code is ported properly.
Potential uses for libraries:
- as a step in porting a Python 2 codebase to Python 3 (e.g. with the ``futurize`` script)
- to provide Python 3 support for previously Python 2-only libraries with the
same APIs as on Python 2 -- particularly with regard to 8-bit strings (the
``past.builtins.str`` type).
- to aid in providing minimal-effort Python 3 support for applications using
libraries that do not yet wish to upgrade their code properly to Python 3, or
wish to upgrade it gradually to Python 3 style.
Here are some code examples that run identically on Python 3 and 2::
>>> from past.builtins import str as oldstr
>>> philosopher = oldstr(u'\u5b54\u5b50'.encode('utf-8'))
>>> # This now behaves like a Py2 byte-string on both Py2 and Py3.
>>> # For example, indexing returns a Python 2-like string object, not
>>> # an integer:
>>> philosopher[0]
'\xe5'
>>> type(philosopher[0])
<past.builtins.oldstr>
>>> # List-producing versions of range, reduce, map, filter
>>> from past.builtins import range, reduce
>>> range(10)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> reduce(lambda x, y: x+y, [1, 2, 3, 4, 5])
15
>>> # Other functions removed in Python 3 are resurrected ...
>>> from past.builtins import execfile
>>> execfile('myfile.py')
>>> from past.builtins import raw_input
>>> name = raw_input('What is your name? ')
What is your name? [cursor]
>>> from past.builtins import reload
>>> reload(mymodule) # equivalent to imp.reload(mymodule) in Python 3
>>> from past.builtins import xrange
>>> for i in xrange(10):
... pass
It also provides import hooks so you can import and use Python 2 modules like
this::
$ python3
>>> from past.translation import autotranslate
>>> authotranslate('mypy2module')
>>> import mypy2module
until the authors of the Python 2 modules have upgraded their code. Then, for
example::
>>> mypy2module.func_taking_py2_string(oldstr(b'abcd'))
Credits
-------
:Author: Ed Schofield, Jordan M. Adler, et al
:Sponsor: Python Charmers: https://pythoncharmers.com
Licensing
---------
Copyright 2013-2024 Python Charmers, Australia.
The software is distributed under an MIT licence. See LICENSE.txt.
"""
from future import __version__, __copyright__, __license__
__title__ = 'past'
__author__ = 'Ed Schofield'
|
