__init__.py 文件源码

def get_arg_default(f, position):
    try:
        # Python >= 3.3
        sig = inspect.signature(f)
        arg = list(sig.parameters.values())[position]
        arg_def = arg.default
        return arg_def if arg_def != inspect.Parameter.empty else None
    except AttributeError:
        try:
            spec = inspect.getfullargspec(f)
        except AttributeError:
            spec = inspect.getargspec(f)

        args_len = len(spec.args)
        if spec.defaults and abs(position - args_len) <= len(spec.defaults):
            return spec.defaults[position - args_len]
        else:
            return None