装饰一个class的具体方法

Question

我阅读了装饰器，我正在尝试装饰 class 没有静态方法的所有方法。

现在我只是使用我为非静态的特定函数编写的装饰器，所以我想知道是否有一种方法既可以装饰很多方法又可以避免静态方法

我用我的装饰器得到了什么：

TypeError: unbound method test() must be called with ClassTest instance as first argument (got nothing instead)

我的装饰师：

def decorator(func):
    def wrapper(self, *args, **kwargs):
        print "test"
        return func(self, *args, **kwargs)
    return wrapper

Answer 1

首先，装饰 class 非常简单：

def class_decorator(cls):
    # modify cls
    return cls

为了 add/remove/modify 方法的功能，您可以使用修饰版本的方法（或变量）调用 setattr：

setattr(some_class, some_attribute, decorator(some_callable))

关于区分不同类型的方法，您可以使用几个属性判断一个方法是否是 instance/class/static 方法。

一个完整的工作示例：

def _is_instance_method(var):
    if not hasattr(var, '__call__'): # It's not a callable
        return False
    if not hasattr(var, 'im_self'): # It's a callable, but it's not a bound method
        return False
    if getattr(var, 'im_self') is not None: # At this point, if it's a class method,
                                            # it will be bound to the class, while
                                            # the instance method is still unbound
                                            # return False if it's bound (i.e. a class method)
        return False
    return True # All that remains is a callable, that's boundable, but not yet -- an instance method!

def func_decorator(func):
    def func_wrapper(self, *args, **kwargs):
        print "Inside %s!" % (func.__name__,)
        return func(self, *args, **kwargs)
    return func_wrapper

def class_decorator(cls):
    for attr in cls.__dict__:
        var = getattr(cls, attr)
        if _is_instance_method(var): # Determine whether the attribute is an instance method
            setattr(cls, attr, func_decorator(var)) # Replace the function with a decorated one
    return cls # Return the class with its new decorated instance methods

@class_decorator
class B(object):

    @staticmethod
    def static_method():
        return "static method"

    @classmethod
    def cls_method(cls):
       return "cls method"

    def instance_method(self):
       return "instance method"

print B.static_method() 
print B.cls_method()
b = B()
print b.instance_method()

装饰一个class的具体方法

decorate specific methods of a class

python

static-methods

decorator