深入浅出分析Python装饰器用法
更新时间:2017年07月28日 10:12:31 作者:罗兵
这篇文章主要介绍了Python装饰器用法,结合实例形式对比分析了Python装饰器的定义与使用技巧,需要的朋友可以参考下
本文实例讲述了Python装饰器用法。分享给大家供大家参考,具体如下:
用类作为装饰器
示例一
最初代码:
class bol(object): def __init__(self, func): self.func = func def __call__(self): return "<b>{}</b>".format(self.func()) class ita(object): def __init__(self, func): self.func = func def __call__(self): return "<i>{}</i>".format(self.func()) @bol @ita def sayhi(): return 'hi'
改进一:
class sty(object): def __init__(self, tag): self.tag = tag def __call__(self, f): def wraper(): return "<{tag}>{res}</{tag}>".format(res=f(), tag=self.tag) return wraper @sty('b') @sty('i') def sayhi(): return 'hi'
改进二:
class sty(object): def __init__(self, *tags): self.tags = tags def __call__(self, f): def wraper(): n = len(self.tags) return "{0}{1}{2}".format(('<{}>'*n).format(*self.tags), f(), ('</{}>'*n).format(*reversed(self.tags))) return wraper @sty('b', 'i') def sayhi(): return 'hi' print(sayhi())
改进三:
class sty(object): def __init__(self, *tags): self.tags = tags def __call__(self, f): def wraper(*args, **kwargs): n = len(self.tags) return "{0}{1}{2}".format(('<{}>'*n).format(*self.tags), f(*args, **kwargs), ('</{}>'*n).format(*reversed(self.tags))) return wraper @sty('b', 'i') def say(word='Hi'): return word print(say()) print(say('Hello'))
示例二
最初代码:
import threading import time class DecoratorClass(object): def __init__(self): self.thread = None def __call__(self, func, *args, **kwargs): def wrapped_func(*args, **kwargs): curr_thread = threading.currentThread().getName() self.thread = curr_thread print('\nthread name before running func:', self.thread) ret_val = func() print('\nthread name after running func:', self.thread) return ret_val return wrapped_func @DecoratorClass() def decorated_with_class(): print('running decorated w class') time.sleep(1) return threads = [] for i in range(5): t = threading.Thread(target=decorated_with_class) threads.append(t) t.setDaemon(True) # 守护 t.start()
改进:进程锁
import threading import time class DecoratorClass(object): def __init__(self): self.thread = None self.lock = threading.Lock() def __call__(self, func, *args, **kwargs): def wrapped_func(*args, **kwargs): self.lock.acquire() curr_thread = threading.currentThread().getName() self.thread = curr_thread print('thread name before running func:', self.thread) ret_val = func() print('\nthread name after running func:', self.thread) self.lock.release() return ret_val return wrapped_func @DecoratorClass() def decorated_with_class(): print('Let me sleep 1 second...') time.sleep(1) return threads = [] for i in range(5): t = threading.Thread(target=decorated_with_class) threads.append(t) t.start()
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