base.py 文件源码

def with_defaults(**default_funcs):
    """
    Decorator for providing dynamic default values for a method.

    Usages:

    @with_defaults(foo=lambda self: self.x + self.y)
    def func(self, foo):
        ...

    If a value is passed for `foo`, it will be used. Otherwise the function
    supplied to `with_defaults` will be called with `self` as an argument.
    """
    def decorator(f):
        @wraps(f)
        def method(self, *args, **kwargs):
            for name, func in iteritems(default_funcs):
                if name not in kwargs:
                    kwargs[name] = func(self)
            return f(self, *args, **kwargs)
        return method
    return decorator