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June 2015

25 participants
31 discussions

distutils package includes, package system includes, and environment-defined system includes
by Poor Yorick 01 Jun '15

01 Jun '15

I maintain a software collection that installs to an alternate prefix, and some of the longstanding issues I've seen with Python packages is that distutils doesn't seem to have any mechanism to allow a package build script to distinguish between project include directories and system include directories, and therefore include_dirs gets used for both purposes. The main issue is that project include directories should preceed anything specified in CPPFLAGS, whereas system include directories should follow CPPFLAGS. I've had a look at distutils2 and the situation is pretty much the same there. I finally decided to spend some time exploring this issue, and ended up creating a fairly extensive modification of the distutils that was shipped with Python-2.7.9, and also of the numpy and scipy packages. They take the approach of having cc_args precede the CPPFLAGS. This leaves extra_compile_args as a possible mechanism for system includes. Links to my patches are below. So far I like the effect they've had. Adding parsed environment variables to "extensions" is a little beyond its stated scope, but it has the benefit of unifying the treatment of command line options and of giving the user the opportunity to bind options tightly to the compiler command by adding options there, or to leave them, for example, in CFLAGS, where they can potentially be overriden by the package distribution. I also like the fact that the modifications make "compiler_exe" and "compiler_so" disappear, and leave "compiler", "compiler_flags_so", and "compiler_flags_exe" instead. That seems like a a cleaner model of the commands involved. I'm considering adding a "sysincludedirs" argument to Extension(). Using the disutils packaged with Python-2.7.9, numpy wasn't doing the right thing, and compiler flags weren't making it into the Fortran command lines. with these modifications and the numpy modifications, things are working better. I would appreciate any feedback anyone interested might have after glancing over the patches. http://dpaste.com/215AF8J http://dpaste.com/0K94JJ2 -- Yorick

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