使用__call__(self,[..)方法将类变成装饰器

Posted 2020-10-12 fuzzier

1 使用__call__(self,[..)方法将类变成装饰器

这里我就用一个例子和执行图来解释了

class Describer(object):

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

    def __call__(self, func):  # func 是 Foo().foo
        print \'im Describer call\'

        def inner(foo_self, *args):  # foo_self是Foo()对象
            print foo_self.name
            return func(foo_self, *args)

        return inner


class Foo(object):

    def __init__(self):
        self.name = \'www\'

    @Describer(\'zhn\')  # 相当于 temp = Describer(__init__); inner = temp__call__(foo); func_result = inner(foo_self, *args)
    def foo(self):
        return \'im Foo instance foo\'


f = Foo()
print f.foo()

result:

im Describer call
www
im Foo instance foo

f.foo() 相当于

temp = Describer(‘zhn’);

inner = temp__call__(foo);

func_result = inner(foo_self, *args)

 

程序执行图

2 使用静态方法或者类方法将类的方法变为装饰器

class Des(object):

    @staticmethod
    def des_func(sth):
        def middle(func):
            def inner(obj, *args):
                print \'first we talk %s\' % sth
                print \'obj is %s\' % obj.name
                return func(obj, *args)

            return inner
        return middle


class Foo(object):

    def __init__(self):
        self.name = \'wwww\'

    @Des.des_func(\'pig\')
    def foo_func(self):
        print \'the func is  foo_func\'
        return


foo = Foo()
foo.foo_func()

# out:
# first we talk pig
# obj is wwww
# the func is  foo_func

 

 

参考

Python Decorators II: Decorator Arguments by Bruce Eckel 地址