mirror of https://github.com/python/cpython
76 lines
2.2 KiB
ReStructuredText
76 lines
2.2 KiB
ReStructuredText
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.. _2to3-reference:
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2to3 - Automated Python 2 to 3 code translation
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===============================================
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.. sectionauthor:: Benjamin Peterson
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2to3 is a Python program that reads your Python 2.x source code and applies a
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series of *fixers* to transform it into valid Python 3.x code.
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Using 2to3
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----------
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2to3 can be run with a list of files to transform or a directory to recursively
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traverse looking for files with the ``.py`` extension.
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Here is a sample Python 2.x source file, :file:`example.py`::
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def greet(name):
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print "Hello, {0}!".format(name)
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print "What's your name?"
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name = raw_input()
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greet(name)
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It can be converted to Python 3.x code via 2to3 on the command line::
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$ 2to3 example.py
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A diff against the original source file will be printed. 2to3 can also write
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the needed modifications right back to the source file. (A backup of the
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original file will also be made.) This is done with the :option:`-w` flag::
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$ 2to3 -w example.py
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:file:`example.py` will now look like this::
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def greet(name):
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print("Hello, {0}!".format(name))
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print("What's your name?")
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name = input()
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greet(name)
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Comments and and exact indentation will be preserved throughout the translation
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process.
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By default, 2to3 will run a set of predefined fixers. The :option:`-l` flag
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lists all avaible fixers. An explicit set of fixers to run can be given by use
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of the :option:`-f` flag. The following example runs only the ``imports`` and
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``has_key`` fixers::
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$ 2to3 -f imports -f has_key example.py
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Some fixers are *explicit*, meaning they aren't run be default and must be
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listed on the command line. Here, in addition to the default fixers, the
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``idioms`` fixer is run::
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$ 2to3 -f all -f idioms example.py
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Notice how ``all`` enables all default fixers.
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Sometimes 2to3 will find will find a place in your source code that needs to be
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changed, but 2to3 cannot fix automatically. In this case, 2to3 will print a
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warning beneath the diff for a file.
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:mod:`lib2to3` - 2to3's library
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-------------------------------
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.. module:: lib2to3
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:synopsis: the 2to3 library
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.. moduleauthor:: Guido van Rossum
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.. moduleauthor:: Collin Winter
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.. XXX What is the public interface anyway?
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