91 lines
2.8 KiB
Python
91 lines
2.8 KiB
Python
# coding=utf-8
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"""
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past: compatibility with Python 2 from Python 3
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===============================================
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``past`` is a package to aid with Python 2/3 compatibility. Whereas ``future``
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contains backports of Python 3 constructs to Python 2, ``past`` provides
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implementations of some Python 2 constructs in Python 3 and tools to import and
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run Python 2 code in Python 3. It is intended to be used sparingly, as a way of
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running old Python 2 code from Python 3 until the code is ported properly.
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Potential uses for libraries:
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- as a step in porting a Python 2 codebase to Python 3 (e.g. with the ``futurize`` script)
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- to provide Python 3 support for previously Python 2-only libraries with the
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same APIs as on Python 2 -- particularly with regard to 8-bit strings (the
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``past.builtins.str`` type).
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- to aid in providing minimal-effort Python 3 support for applications using
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libraries that do not yet wish to upgrade their code properly to Python 3, or
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wish to upgrade it gradually to Python 3 style.
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Here are some code examples that run identically on Python 3 and 2::
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>>> from past.builtins import str as oldstr
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>>> philosopher = oldstr(u'\u5b54\u5b50'.encode('utf-8'))
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>>> # This now behaves like a Py2 byte-string on both Py2 and Py3.
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>>> # For example, indexing returns a Python 2-like string object, not
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>>> # an integer:
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>>> philosopher[0]
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'\xe5'
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>>> type(philosopher[0])
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<past.builtins.oldstr>
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>>> # List-producing versions of range, reduce, map, filter
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>>> from past.builtins import range, reduce
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>>> range(10)
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[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
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>>> reduce(lambda x, y: x+y, [1, 2, 3, 4, 5])
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15
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>>> # Other functions removed in Python 3 are resurrected ...
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>>> from past.builtins import execfile
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>>> execfile('myfile.py')
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>>> from past.builtins import raw_input
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>>> name = raw_input('What is your name? ')
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What is your name? [cursor]
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>>> from past.builtins import reload
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>>> reload(mymodule) # equivalent to imp.reload(mymodule) in Python 3
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>>> from past.builtins import xrange
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>>> for i in xrange(10):
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... pass
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It also provides import hooks so you can import and use Python 2 modules like
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this::
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$ python3
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>>> from past.translation import autotranslate
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>>> authotranslate('mypy2module')
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>>> import mypy2module
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until the authors of the Python 2 modules have upgraded their code. Then, for
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example::
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>>> mypy2module.func_taking_py2_string(oldstr(b'abcd'))
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Credits
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-------
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:Author: Ed Schofield, Jordan M. Adler, et al
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:Sponsor: Python Charmers Pty Ltd, Australia: http://pythoncharmers.com
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Licensing
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---------
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Copyright 2013-2019 Python Charmers Pty Ltd, Australia.
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The software is distributed under an MIT licence. See LICENSE.txt.
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"""
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from future import __version__, __copyright__, __license__
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__title__ = 'past'
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__author__ = 'Ed Schofield'
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