build_py.py 文件源码

def check_package(self, package, package_dir):
        # Empty dir name means current directory, which we can probably
        # assume exists.  Also, os.path.exists and isdir don't know about
        # my "empty string means current dir" convention, so we have to
        # circumvent them.
        if package_dir != "":
            if not os.path.exists(package_dir):
                raise DistutilsFileError(
                      "package directory '%s' does not exist" % package_dir)
            if not os.path.isdir(package_dir):
                raise DistutilsFileError(
                       "supposed package directory '%s' exists, "
                       "but is not a directory" % package_dir)

        # Require __init__.py for all but the "root package"
        if package:
            init_py = os.path.join(package_dir, "__init__.py")
            if os.path.isfile(init_py):
                return init_py
            else:
                log.warn(("package init file '%s' not found " +
                          "(or not a regular file)"), init_py)

        # Either not in a package at all (__init__.py not expected), or
        # __init__.py doesn't exist -- so don't return the filename.
        return None