20011701python函数嵌套_python wraps 多层嵌套-优快云博客

本文链接：https://blog.youkuaiyun.com/jayed008/article/details/104021249

本文深入探讨了Python装饰器的使用方法，包括基本装饰器、带参数的装饰器，以及如何通过多层函数嵌套实现高级功能。通过具体示例，读者可以了解到装饰器在实际编程中的应用，以及如何利用多层嵌套提高代码的灵活性和效率。

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1、装饰器

from functools import wraps
import datetime

def logging(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        """print log before a function."""
        print('[DEBUG] {}: enter {}()'.format(datetime.now(), func.__name__))
        return func(*args, **kwargs)
    return wrapper

@logging
def say(something):
    """say something"""
    print('say {}!'.format(something))

print(say.__name__)  # say
print(say.__doc__) # say something

2、带参数的装饰器

class logging(object):
    def __init__(self, level='INFO'):
        self.level = level

    def __call__(self, func):  # 接受函数
        def wrapper(*args, **kwargs):
            print('[{level}]: enter function {func}()'.format(
                level=self.level,
                func=func.__name__))
            func(*args, **kwargs)

        return wrapper  # 返回函数

@logging(level='INFO')
def say(something):
    print('say {}'.format(something))

say('love you.')
print(say.__name__)  # wrapper

3、多层函数嵌套

import threading, sys
 
def nested1(timeout):
    def _1(function):
        def _2(*args,**kw):
            class child(threading.Thread):
                def __init__(self):
                    threading.Thread.__init__(self)
                    self.result=None
                    self.error = None
                    
                    self.setDaemon(True)
                    self.start()
 
                def run(self):
                    try:
                        self.result = function(*args, **kw)
                    except:
                        self.error = sys.exc_info()
 
            c = child()
            c.join(timeout)
            if c.isAlive():
                raise TimeoutError, 'took too long'
            if c.error:
                raise c.error[0], c.error[1]
            return c.result
        return _2
    return _1
def test(a, b):
    for i in xrange(100000):
        a = a+b
    return a
 
 
if __name__ == '__main__':
    nested1 = nested1(2)
    nested2 = nested1(test)
    print nested2(2,3)
 
    a =  nested2.child()
    print a