python ------ decorator

Introduction

Decorator: essentially function, function is to add additional functionality to other function
principles:
1, does not modify the source code to be modified function
2, does not modify the modified function is called

Knowledge base decorator
decorator higher order function = + + nested closure function

Simple decorator

import time
#装饰器的架子
def timmer(func):# func = test
    def wrapper():        
        #print(func)
        start_time = time.time()
        func()#就是在运行test()
        stop_time = time.time()
        print("运行时间就是%s" % (stop_time - start_time))
    return wrapper

def test():
    time.sleep(3)
    print("test函数运行完毕")
    
test = timmer(test)#返回的是wrapper的地址
test()#执行的是wrapper()

Syntax pond

@timmer equivalent test = timmer (test)

import time
#装饰器的架子
def timmer(func):# func = test
    def wrapper():        
        #print(func)
        start_time = time.time()
        func()#就是在运行test()
        stop_time = time.time()
        print("运行时间就是%s" % (stop_time - start_time))
    return wrapper


@timmer
def test():
    time.sleep(3)
    print("test函数运行完毕")
    
#test = timmer(test)#返回的是wrapper的地址
test()#执行的是wrapper()