After a bit of a struggle I finally got RFFI working for a shared libary I had compiled. I found a few strange discrepancies in the behavior of ExternalCompilitionInfo on OSX I thought may benefit from fixes to make behavior more consistent.
=== RPython Translation vs. Python Execution Strangeness === Given a shared library I had compiled named libsoftfloat.so: - ExternalCompilationInfo( libraries = ['libsoftfloat'] ) and libname == libsoftfloat.so - python execution: Error: "cannot find library libsoftfloat" - rpython translation: Error: "ld: library not found for -llibsoftfloat" - ExternalCompilationInfo( libraries = ['softfloat'] ) and libname == libsoftfloat.so - python execution: Error: "cannot find library softfloat" - rpython translation: Works! The problem with RFFI during Python execution appears to be that on OSX it checks for the library suffix of .dylib, **not** .so: - ExternalCompilationInfo( libraries = ['libsoftfloat'] ) and libname == libsoftfloat.dylib - python execution: Works! - rpython translation: Error: "ld: library not found for -llibsoftfloat" - ExternalCompilationInfo( libraries = ['softfloat'] ) and libname == libsoftfloat.dylib - python execution: Works! - rpython translation: Works! Some naming schemes work on just python execution, some on just rpython translation. It would be nice if these failed/worked consistently in both modes. In particular, I think on OSX the library lookup for RFFI should look for both .so and .dylib, not just .dylib since it seems to be fairly common practice to generate .so files? Also, the libraries naming convention passed to ExternalCompilationInfo is a bit inconsistent/foreign for someone coming from CFFI and using ffi.dlopen(). === Documentation === I really couldn't figure out how to use RFFI from the RPython docs or from the PyPy source. I started off using these resources: - https://rpython.readthedocs.org/en/latest/rffi.html - https://bitbucket.org/pypy/pypy/src/tip/rpython/rlib/_rsocket_rffi.py - https://bitbucket.org/pypy/pypy/src/tip/pypy/module/crypt/interp_crypt.py The only way I really figured out how to use it was from this patch submitted by the libgccjit guy that had some simple examples on how to use RFFI: - https://mail.python.org/pipermail/pypy-dev/2014-December/012947.html What would be really nice is some example of how to write a simple function in C, compile it into a shared library, and use it via RFFI. Even better, an example mapping a CFFI use case to the RFFI interface. I personally learn how to use APIs much more easily with concrete examples; for example, I created a little git repo as a self-demonstration of how to use the new CFFI APIs with a non-trivial library: - https://github.com/dmlockhart/python-softfloat-cffi/ I'd be willing to help a bit with the docs, if it's agreed updates would be appreciated. Derek
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