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diff --git a/docs/python3.txt b/docs/python3.txt new file mode 100644 index 00000000..19a2b268 --- /dev/null +++ b/docs/python3.txt @@ -0,0 +1,120 @@ +===================================================== +Supporting both Python 2 and Python 3 with Distribute +===================================================== + +Starting with version 0.6.2, Distribute supports Python 3. Installing and +using distribute for Python 3 code works exactly the same as for Python 2 +code, but Distribute also helps you to support Python 2 and Python 3 from +the same source code by letting you run 2to3 on the code as a part of the +build process. by setting the keyword parameter ``run_2to3`` to True. + + +Distrubute as help during porting +================================= + +Distribute can make the porting process much easier by automatically running +2to3 as a part of the test running. To do this you need to configure the +setup.py so that you can run the unit tests with ``python setup.py test``. + +See :ref:`test` for more information on this. + +Once you have the tests running under Python 2, you can add the run_2to3 +keyword parameters to setup(), and start running the tests under Python 3. +The test command will now first run the build command during which the code +will be converted with 2to3, and the tests will then be run from the build +directory, as opposed from the source directory as is normally done. + +Distribute will convert all Python files, and also all doctests in Python +files. However, if you have doctests located in separate text files, these +will not automatically be converted. By adding them to the +``convert_doctests_2to3`` keyword parameter Distrubute will convert them as +well. + +By default, the conversion uses all fixers in the ``lib2to3.fixers`` package. +To use additional fixes, the parameter ``additional_2to3_fixers`` can be set +to a list of names of packages containing fixers. + +A typical setup.py can look something like this:: + + from setuptools import setup + + setup(name='your.module', + version = '1.0', + description='This is your awesome module', + author='You', + author_email='your@email', + package_dir = {'': 'src'}, + packages = ['your', 'you.module'], + test_suite = 'your.module.tests', + run_2to3 = True, + convert_doctests_2to3 = ['src/your/module/README.txt'], + additional_2to3_fixers = ['your.fixers'] + ) + +Differential conversion +----------------------- + +Note that a file will only be copied and converted during the build process +if the source file has been changed. If you add a file to the doctests +that should be converted, it will not be converted the next time you run +the tests, since it hasn't been modified. You need to remove it from the +build directory. Also if you run the build, install or test commands before +adding the run_2to3 parameter, you will have to remove the build directory +before you run the test command, as the files otherwise will seem updated, +and no conversion will happen. + +In general, if code doesn't seem to be converted, deleting the build directory +and trying again is a good saferguard against the build directory getting +"out of sync" with teh source directory. + +Distributing Python 3 modules +============================= + +You can distribute your modules with Python 3 support in different ways. A +normal source distribution will work, but can be slow in installing, as the +2to3 process will be run during the install. But you can also distribute +the module in binary format, such as a binary egg. That egg will contain the +already converted code, and hence no 2to3 conversion is needed during install. + +Advanced features +================= + +If certain fixers are to be suppressed, this again can be overridden with the +list ``setuptools.commands.build_py.build_py.fixers``, which then contains the +list of all fixer class names. + +If you don't want to run the 2to3 conversion on the doctests in Python files, +you can turn that off by setting ``setuptools.run_2to3_on_doctests = False``. + +Note on compatibility with setuptools +===================================== + +Setuptools do not know about the new keyword parameters to support Python 3. +As a result it will warn about the unknown keyword parameters if you use +setuptools instead of Distribute under Python 2. This is not an error, and +install process will continue as normal, but if you want to get rid of that +error this is easy. Simply conditionally add the new parameters into an extra +dict and pass that dict into setup():: + + from setuptools import setup + import sys + + extra = {} + if sys.version_info >= (3,): + extra['run_2to3'] = True + extra['convert_doctests_2to3'] = ['src/your/module/README.txt'] + extra['additional_2to3_fixers'] = ['your.fixers'] + + setup(name='your.module', + version = '1.0', + description='This is your awesome module', + author='You', + author_email='your@email', + package_dir = {'': 'src'}, + packages = ['your', 'you.module'], + test_suite = 'your.module.tests', + **extra + ) + +This way the parameters will only be used under Python 3, where you have to +use Distribute. |
