创建一个包装器类来围绕现有函数调用前置和后置函数?

__getattr__ ,当原始属性可调用时,返回一个新的包装函数:

class Wrapper(object):
    def __init__(self,wrapped_class):
        self.wrapped_class = wrapped_class()

    def __getattr__(self,attr):
        orig_attr = self.wrapped_class.__getattribute__(attr)
        if callable(orig_attr):
            def hooked(*args, **kwargs):
                self.pre()
                result = orig_attr(*args, **kwargs)
                # prevent wrapped_class from becoming unwrapped
                if result == self.wrapped_class:
                    return self
                self.post()
                return result
            return hooked
        else:
            return orig_attr

    def pre(self):
        print ">> pre"

    def post(self):
        print "<< post"

number = Wrapper(Simple)

print "\nCalling wrapped 'one':"
number.one()

print "\nCalling wrapped 'two':"
number.two("2")

Calling wrapped 'one':
>> pre
one
<< post

Calling wrapped 'two':
>> pre
two2
<< post

我刚刚注意到,在我的原始设计中,无法将args和kwargs传递给包装类,以下是更新的答案,将输入传递给包装函数。..

class Wrapper(object):
def __init__(self,wrapped_class,*args,**kargs):
    self.wrapped_class = wrapped_class(*args,**kargs)

def __getattr__(self,attr):
    orig_attr = self.wrapped_class.__getattribute__(attr)
    if callable(orig_attr):
        def hooked(*args, **kwargs):
            self.pre()
            result = orig_attr(*args, **kwargs)
            self.post()
            return result
        return hooked
    else:
        return orig_attr

def pre(self):
    print ">> pre"

def post(self):
    print "<< post"