[Distutils] optional binary compilation under future installation tools

[Tarek Ziadé]

On 9/13/12 10:15 AM, Chris McDonough wrote:
> Some packages we maintain currently provide largely identical
> side-by-side implementations of features: one implementation is written
> in C, the other implementation is written in Python.  The C module is
> just an optimized version of the Python code.
>
> There is logic at module scope within modules in the same package which
> attempts to import the C version.  If the C version cannot be imported
> (an ImportError is raised), the logic falls back to importing the Python
> version:
>
> try:
>      from . import cmodule as module
> except ImportError
>      from . import pymodule as module
>
> This means that the package can be used if the C implementation is
> compiled or not.  It will run more slowly, but that's OK in lots of
> cases.
>
> In our setup.py for these kinds of distributions, we have code which
> under Py2 uses a setuptools "feature" and under Py3 registers a
> different kind of build_ext which, at install time, will:
>
> - Attempt to compile the C if suitable build tools seem to exist on the
>    target system.
>
> - If suitable build tools don't seem to exist on the target system, will
>    print a message and continue.
>
> How can we support such a feature in the brave new declarative packaging
> world?
>
> - C
>
FWIW there's an 'optional' option for the Extension class in Python 2.7 
in distutils.

see 
http://hg.python.org/cpython/file/9b40d018e4cf/Lib/distutils/command/build_ext.py#l458

If the compilation fails it just warns and continues.

That option is also present in distutils2, so you can use it in the 
setup.cfg file.

Does that work ?

Cheers
Tarek




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