python裝飾器應用

1.簡單註冊表

funcs = []
def register(func):
    funcs.append(func)
    return func
    
    
@register
def a():
    return 3
    
@register
def b():
    return 5
    


result = [func() for func in funcs]
# 訪問結果
# [3,5]

 

2.接收rabbit包，根據包字段不同註冊不同函數調用

class MqModel:
    def __init__(self):
        self.registryCenter = {}

    def msg_dispacher(self,body, message):
        """
        數據分發
        :param body:
        :param message:
        :return:
        """

        try:
            jdata = json.loads(body)
            head = jdata['head']
        except ValueError:
            print("Not support non-json msg",body)
            message.ack()
            return
        finally:
            if 'op' not in head:
                message.ack()
                print("special msg ERROR", body)
                return
        if head['op'] in self.registryCenter:
            for func in self.registryCenter[head['op']]:
                func(jdata)
        else:
            print("jdata['op'] not in self.registryCenter:")


def registryConsumer(msgtype):

    def wrapper(func):
        if  msgtype in mqModel.registryCenter:
            mqModel.registryCenter[msgtype].append(func)
        else:
            mqModel.registryCenter[msgtype]=[func]

    return wrapper



@registryConsumer('web-phone-update')
def receive_statusMsg(body):
    """
    註冊收報回調
    :param body:
    :param message:
    :return:
    """
 print('web-phone-update')
    print(body)

3.使用裝飾器在函數前後添加一行Log

def log(function):
    def wrapper(*args,**kwargs):
        print('before func')
        res = function(*args,**kwargs)
        print('after func')
        return res
    return wrapper

@log
def func(str):
    print('execute func %s' % str)

4.使用帶參數的裝飾器

import functools


def log(text):
    def decorate(function):
        @functools.wraps(function)
        def wrapper(*args, **kwargs):
            print('%s before func' % text)
            res = function(*args, **kwargs)
            print('%s after func' % text)
            return res

        return wrapper

    return decorate


@log('param')
def func(str):
    print('execute func %s' % str)

5.裝飾器實現的單例模式

def singleton(cls, *args, **kwargs):
    instance = {}

    def _singleton():
        if cls not in instance:
            instance[cls] = cls(*args, **kwargs)
        return instance[cls]
    return _singleton

@singleton
class test_singleton(object):
    name = None

    def __init__(self):
        self.sum = 0

    def add(self, name):
        self.name = name

if __name__ == '__main__':
    cls1 = test_singleton()
    cls1.add('cls1')
    cls2 = test_singleton()
    cls2.add('cls2')
    cls3 = test_singleton()
    cls3.add('cls3')
    print(cls1)
    print(cls2)
    print(cls3)
    print(cls1.name)
    print(cls2.name)
    print(cls3.name)