[Distutils] setuptools' "Feature" feature
tseaver at palladion.com
Fri Jul 2 20:29:20 CEST 2010
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I haven't found any docs (outside the code) for the
setuptools.dist.Feature, or for how it operates with the rest of the
ecosystem. Can somebody confirm or correct my understanding of them?
- - Feature instances represent optionally-included bits of the
- - Normally, features are disabled by default, and can be enabled
by passing '--with-<featurename>' to setup.py.
- - Features declared as 'standard' are enabled by default, and can be
disabled by passing '--without-<featurename>' to setup.py.
- - Features have an 'available' attribute, which can be set to False
in setup.py to disable a feature based on runtime introspection
(e.g., using sys.version_info or os.name).
- - It appears that it should be possible to pass an instance with
a '__nonzero__' method as the 'available': the code seems only
to use it in boolean tests.
- - Features may depend on (force inclusion of) other features.
- - Enabled features do their actual work by adding **kwargs to
the args passed directly to setup.py
- - Distributions created via an invocation to setup.py are not labeled
in any way to indicate any '--with-<featurename>' (or '--without')
passed to setup.py during their creation.
- - There is no way to enable / disable a feature when installing a
distribution via easy_install.
The particular use case which led me to investigate Features was easing
packaging of projects with optional C extensions, such that they could
be installable on Jython, IronPython, Windows, or GAE. It doesn't seem
possible to figure out whether a compiler actually exists: jython's
distutils lies and creates a compiler which raises exceptions, for instance.
Tres Seaver +1 540-429-0999 tseaver at palladion.com
Palladion Software "Excellence by Design" http://palladion.com
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