cpython/Doc/library/future_builtins.rst

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:mod:`future_builtins` --- Python 3 built-ins
=============================================
.. module:: future_builtins
.. sectionauthor:: Georg Brandl
.. versionadded:: 2.6
This module provides functions that exist in 2.x, but have different behavior in
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Python 3, so they cannot be put into the 2.x builtins namespace.
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Instead, if you want to write code compatible with Python 3 built-ins, import
them from this module, like this::
from future_builtins import map, filter
... code using Python 3-style map and filter ...
The :term:`2to3` tool that ports Python 2 code to Python 3 will recognize
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this usage and leave the new built-ins alone.
.. note::
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The Python 3 :func:`print` function is already in the built-ins, but cannot be
accessed from Python 2 code unless you use the appropriate future statement::
from __future__ import print_function
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Available built-ins are:
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.. function:: ascii(object)
Returns the same as :func:`repr`. In Python 3, :func:`repr` will return
printable Unicode characters unescaped, while :func:`ascii` will always
backslash-escape them. Using :func:`future_builtins.ascii` instead of
:func:`repr` in 2.6 code makes it clear that you need a pure ASCII return
value.
.. function:: filter(function, iterable)
Works like :func:`itertools.ifilter`.
.. function:: hex(object)
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Works like the built-in :func:`hex`, but instead of :meth:`__hex__` it will
use the :meth:`__index__` method on its argument to get an integer that is
then converted to hexadecimal.
.. function:: map(function, iterable, ...)
Works like :func:`itertools.imap`.
.. function:: oct(object)
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Works like the built-in :func:`oct`, but instead of :meth:`__oct__` it will
use the :meth:`__index__` method on its argument to get an integer that is
then converted to octal.
.. function:: zip(*iterables)
Works like :func:`itertools.izip`.