setuptools_ext.py 文件源码

def _set_py_limited_api(Extension, kwds):
    """
    Add py_limited_api to kwds if setuptools >= 26 is in use.
    Do not alter the setting if it already exists.
    Setuptools takes care of ignoring the flag on Python 2 and PyPy.

    CPython itself should ignore the flag in a debugging version
    (by not listing .abi3.so in the extensions it supports), but
    it doesn't so far, creating troubles.  That's why we check
    for "not hasattr(sys, 'gettotalrefcount')" (the 2.7 compatible equivalent
    of 'd' not in sys.abiflags). (http://bugs.python.org/issue28401)
    """
    if 'py_limited_api' not in kwds and not hasattr(sys, 'gettotalrefcount'):
        import setuptools
        try:
            setuptools_major_version = int(setuptools.__version__.partition('.')[0])
            if setuptools_major_version >= 26:
                kwds['py_limited_api'] = True
        except ValueError:  # certain development versions of setuptools
            # If we don't know the version number of setuptools, we
            # try to set 'py_limited_api' anyway.  At worst, we get a
            # warning.
            kwds['py_limited_api'] = True
    return kwds