[Cython] Cython 0.17 beta 1 released

[Yaroslav Halchenko]

On Wed, 25 Jul 2012, Robert Bradshaw wrote:

> One essential feature of cython.inline(...) is that if the code has
> already been compiled (and loaded) it should return very fast. This
> would seem to add significant overhead. 

that is what was my concern also with such an approach...  I am not sure
if that is a significant overhead -- on my laptop (python 2.7):

In [13]: !cat test_get_ext_time.py
from distutils.core import Distribution
from distutils.command.build_ext import build_ext

def get_ext_filename(module_name):
    dist = Distribution()
    # Ensure the build respects distutils configuration by parsing
    # the configuration files
    config_files = dist.find_config_files()
    dist.parse_config_files(config_files)
    build_extension = build_ext(dist)
    build_extension.finalize_options()

    return build_extension.get_ext_filename(module_name)

In [14]: %run test_get_ext_time.py

In [15]: %timeit get_ext_filename('/asd/f.asdf/asdf/asd/fasdf/xx')
1000 loops, best of 3: 301 us per loop

of cause it is a relatively big slowdown relatively to 3ms of solution
based on imp.get_suffixes ...  and with cython 0.16 full dummy inline:

In [4]: %timeit cython_inline('i=1')
1000 loops, best of 3: 445 us per loop

so I guess indeed 300 us would be a significant overhead

> Is the extension relatively
> consistant? Perhaps it could be cached at module load time.

could indeed be especially given the code of

    def get_ext_filename(self, ext_name):
        r"""Convert the name of an extension (eg. "foo.bar") into the name
        of the file from which it will be loaded (eg. "foo/bar.so", or
        "foo\bar.pyd").
        """
        from distutils.sysconfig import get_config_var
        ext_path = ext_name.split('.')
        # OS/2 has an 8 character module (extension) limit :-(
        if os.name == "os2":
            ext_path[len(ext_path) - 1] = ext_path[len(ext_path) - 1][:8]
        # extensions in debug_mode are named 'module_d.pyd' under windows
        so_ext = get_config_var('SO')
        if os.name == 'nt' and self.debug:
            return os.path.join(*ext_path) + '_d' + so_ext
        return os.path.join(*ext_path) + so_ext

suggesting only get_config_var and 1 self.debug variable which could affect .. which are probably would not be changed at run time.  Paranoid me
though would still have added some check when extension does get built to
verify that assumption was right and then spit out a warning and adjust
module_name to match so that load_dynamic  doesn't fail... or would that be too
much?

would you like me to prep a perspective path or you would like to do that? ;)

-- 
Yaroslav O. Halchenko
Postdoctoral Fellow,   Department of Psychological and Brain Sciences
Dartmouth College, 419 Moore Hall, Hinman Box 6207, Hanover, NH 03755
Phone: +1 (603) 646-9834                       Fax: +1 (603) 646-1419
WWW:   http://www.linkedin.com/in/yarik