misc.py 文件源码

def _get_arg_lengths(func):
    """Returns a two-tuple containing the number of positional arguments
    as the first item and the number of variable positional arguments as
    the second item.
    """
    try:
        funcsig = inspect.signature(func)
        params_dict = funcsig.parameters
        parameters = params_dict.values()
        args_type = (inspect._POSITIONAL_OR_KEYWORD, inspect._POSITIONAL_ONLY)
        args = [x for x in parameters if x.kind in args_type]
        vararg = [x for x in parameters if x.kind == inspect._VAR_POSITIONAL]
        vararg = vararg.pop() if vararg else None
    except AttributeError:
        try:
            try:  # For Python 3.2 and earlier.
                args, vararg = inspect.getfullargspec(func)[:2]
            except AttributeError:  # For Python 2.7 and earlier.
                args, vararg = inspect.getargspec(func)[:2]
        except TypeError:     # In 3.2 and earlier, raises TypeError
            raise ValueError  # but 3.3 and later raise a ValueError.
    return (len(args), (1 if vararg else 0))