Python3 装饰器之 wraps

我们在使用 Decorator 的过程中，难免会损失一些原本的功能信息。

请参见如下实例：

def logged(func):
    def with_logging(*args, **kwargs):
        print(func.__name__ + " was called")
        return func(*args, **kwargs)
    return with_logging

@logged
def f(x):
   """does some math"""
   return x + x * x

def f(x):
    """does some math"""
    return x + x * x
f = logged(f)

In [24]: f.__name__
Out[24]: with_logging

而functools.wraps 则可以将原函数对象的指定属性复制给包装函数对象, 默认有 module、name、doc,或者通过参数选择。代码如下：

from functools import wraps
def logged(func):
    @wraps(func)
    def with_logging(*args, **kwargs):
        print(func.__name__ + " was called")
        return func(*args, **kwargs)
    return with_logging

@logged
def f(x):
   """does some math"""
   return x + x * x

print(f.__name__)  # prints 'f'
print(f.__doc__)   # prints 'does some math'