easy_install.py 文件源码

def _expand(self, *attrs):
        config_vars = self.get_finalized_command('install').config_vars

        if self.prefix or self.install_layout:
            if self.install_layout and self.install_layout.lower() in ['deb']:
                    scheme_name = "deb_system"
                    self.prefix = '/usr'
            elif self.prefix or 'real_prefix' in sys.__dict__:
                scheme_name = os.name
            else:
                scheme_name = "posix_local"
            # Set default install_dir/scripts from --prefix
            config_vars = config_vars.copy()
            config_vars['base'] = self.prefix
            scheme = self.INSTALL_SCHEMES.get(scheme_name,self.DEFAULT_SCHEME)
            for attr, val in scheme.items():
                if getattr(self, attr, None) is None:
                    setattr(self, attr, val)

        from distutils.util import subst_vars

        for attr in attrs:
            val = getattr(self, attr)
            if val is not None:
                val = subst_vars(val, config_vars)
                if os.name == 'posix':
                    val = os.path.expanduser(val)
                setattr(self, attr, val)