decorator.py 文件源码

def preserve_signature(func):
    """Preserve the original function signature and attributes in decorator wrappers."""
    def fix_signature(wrapper):
        exec_scope = {}
        parameters = formatargspec(*getargspec(func), formatvalue=lambda value: "")
        exec "def {0}{1}: return wrapper{1}".format(func.__name__, parameters) in {'wrapper': wrapper}, exec_scope  # can't use tuple form here (see https://bugs.python.org/issue21591)
        new_wrapper = exec_scope.pop(func.__name__)
        new_wrapper.__name__ = func.__name__
        new_wrapper.__doc__ = func.__doc__
        new_wrapper.__module__ = func.__module__
        new_wrapper.__defaults__ = func.__defaults__
        new_wrapper.__dict__.update(func.__dict__)
        return new_wrapper
    return fix_signature