python class as decorator

关于decorator的官方描述如下：(http://docs.python.org/glossary.html)

decorator

A function returning another function, usually applied as a function transformation using the @wrapper syntax. Common examples for decorators are classmethod() and staticmethod().

The decorator syntax is merely syntactic sugar, the following two function definitions are semantically equivalent:

def f(...):
    ...
f = staticmethod(f)

@staticmethod
def f(...):
    ...

The same concept exists for classes, but is less commonly used there. See the documentation for function definitions and class definitionsfor more about decorators.

这里仅仅演示用一个类作为decorator， 其实主要就是类要包含__call__方法，有关__call__可以参考这里http://www.cnblogs.com/john2000/archive/2012/03/27/2418981.html

 

#encoding:utf-8
"""
    class as decorator
"""

import time

class A:
    def __init__(self, func):
        print "__init__"
        
    def __call__(self):
        time.sleep(10)
        print "__call__"
        
@A
def test():    #编译器将把这里解释为 instanceA = A(test), 当我们调用test的时候实际上调用的是instanceA (*args),即instanceA.__call__(*args)

    print "test"
    
if __name__ =="__main__":
    test()