如何将 python 装饰器应用于函数？ [复制]

Question

可能重复：
Understanding Python decorators

您能否给出一个解释装饰器的简短代码示例？

Answer 1

def spam(func):
    def wrapped(*args, **kwargs):
        print "SPAM"
        return func(*args, **kwargs)
    return wrapped

@spam #this is the same as doing eggs = spam(eggs)
def eggs():
    print "Eggs?"

请注意，您也可以使用类来编写装饰器

class Spam(object):
    def __init__(self, func):
        self.func = func

    def __repr__(self):
        return repr(self.func)

    def __call__(self, *args, **kwargs):
        print "SPAM"
        return self.func(*args, **kwargs)

@Spam
def something():
    pass

Answer 2

装饰器接受函数定义并创建一个执行此函数的新函数 函数并转换结果。

@deco
def do():
    ...

相当于：

do = deco(do)

例子：

def deco(func):
    def inner(letter):
        return func(letter).upper()  #upper
    return inner  # return a function object

#This
@deco
def do(number):
    return chr(number)  # number to letter
#end

# is equivalent to this
def do2(number):
    return chr(number)

do2 = deco(do2)
#end


# 65 <=> 'a'
print(do(65))
print(do2(65))
>>> B
>>> B

要理解装饰器，重要的是要注意，装饰器创建了一个新函数do，它是inner，它执行func并转换结果。