是否可以检索基类中定义的装饰器生成的子类中的值？

Question

我有一个子类的方法，我想有条件地短路。我想做的是类似这样的事情，只是我想把验证逻辑放到基类中。你知道吗

class BaseClass(object):
    def getvalue(self):
        return True
    def validate(self):
        validated = self.getvalue()
        return validated

class ExtendedClass1(BaseClass):
    def do_some_work(self):
        validated = self.validate()
        if not validated:
            print "Not validated."
            return
        print "Things are validated if the method got this far.", validated

class ExtendedClass2(BaseClass):
    def do_some_work(self):
        validated = self.validate()
        if not validated:
            print "Not validated."
            return
        print "Things are validated if the method got this far.", validated

class ExtendedClass3(BaseClass):
    def do_some_work(self):
        print "This one doesn't require validation."

work1 = ExtendedClass1()
work1.do_some_work()

work2 = ExtendedClass2()
work2.do_some_work()

work3 = ExtendedClass3()
work3.do_some_work()

遵循this示例，我能够将一些重复的代码转换为装饰器模式。你知道吗

class BaseClass(object):

    def validate(input_function):
        def wrapper(*args,**kwargs):
            validated = True
            if not validated:
                print "Not validated."
                return
            input_function(*args, **kwargs)
        return wrapper

    validate = staticmethod(validate)

class ExtendedClass1(BaseClass):
    @BaseClass.validate
    def do_some_work(self):
        print "Things are validated if the method got this far."

class ExtendedClass2(BaseClass):
    @BaseClass.validate
    def do_some_work(self):
        print "Things are validated if the method got this far."

class ExtendedClass3(BaseClass):
    def do_some_work(self):
        print "This one doesn't require validation."

work1 = ExtendedClass1()
work1.do_some_work()

work2 = ExtendedClass2()
work2.do_some_work()

work3 = ExtendedClass3()
work3.do_some_work()

但是，我需要在decorator中调用基类的方法来执行验证工作，并在子类中检索（validated）的值。在这个例子here之后，我修改了decorator，试图让它调用self.getvalue(). 在这一点上，它没有出错，但也不起作用，因为self.getvalue（）不返回True。这似乎是开始比它的价值更多的麻烦，但现在我好奇是否有可能。你知道吗

class BaseClass(object):

    def getvalue(self):
        return True

    def validate(self):
        def wrap(input_function):
            def wrapper(*args,**kwargs):
                validated = self.getvalue()
                if not validated:
                    print "Not validated."
                    return
                input_function(*args, **kwargs)
            return wrapper
        return wrap

    validate = staticmethod(validate)

class ExtendedClass1(BaseClass):
    @BaseClass.validate
    def do_some_work(self):
        print "Things are validated if the method got this far."#, validated

class ExtendedClass2(BaseClass):
    @BaseClass.validate
    def do_some_work(self):
        print "Things are validated if the method got this far."#, validated

class ExtendedClass3(BaseClass):
    def do_some_work(self):
        print "This one doesn't require validation."

work1 = ExtendedClass1()
work1.do_some_work()

work2 = ExtendedClass2()
work2.do_some_work()

work3 = ExtendedClass3()
work3.do_some_work()

是否可以用decorator设置一个属性，然后稍后再检索它？你知道吗

                ...
                self.validated = True
                if not self.validated:
                    print "Not validated."
                    return
                ...
print work1.validated
                ...

AttributeError: 'ExtendedClass1' object has no attribute 'validated'

基本上，我想扭转这个局面：

class ExtendedClass1(BaseClass):
    def do_some_work(self):
        validated = self.validate()
        if not validated:
            print "Not validated."
            return
        print "Things are validated if the method got this far.", validated

对此：

class ExtendedClass1(BaseClass):
    @BaseClass.validate
    def do_some_work(self):
        print "Things are validated if the method got this far.", validated

使用zaurnasibov发布的建议，这个例子满足了我的用例。我仍然很想知道@validate是否可以作为一个方法而不是一个独立的函数来实现，但是这样就完成了任务。你知道吗

class BaseClass(object):
    def getvalue(self):
        return True

def validate(func):
    def wrapped(self, *args, **kwargs):
        validated = self.getvalue()
        self.validated = validated
        if not validated:
            print "Not validated."
            return
        func(self, *args, **kwargs)
    return wrapped

class ExtendedClass1(BaseClass):
    @validate
    def do_some_work(self,input):
        print "Things are validated if the method got this far.", self.validated, input

class ExtendedClass2(BaseClass):
    @validate
    def do_some_work(self):
        print "Things are validated if the method got this far.", self.validated

class ExtendedClass3(BaseClass):
    def do_some_work(self):
        print "This one doesn't require validation."#, self.validated

work1 = ExtendedClass1()
work1.do_some_work(input="some text")

work2 = ExtendedClass2()
work2.do_some_work()

work3 = ExtendedClass3()
work3.do_some_work()

Answer 1

@tponthieux，您可以设置被调用函数（方法）的属性，然后检索它：

简单示例（更新了）：

def validate(func):    
    def wrapped(self, *args, **kwargs):
        self.valid = True
        func(self, *args, **kwargs)
    return wrapped

class TestClass(object):
    @validate
    def do_some_work(self):
        print "some work done"

tc = TestClass()
tc.do_some_work()
print tc.valid

Answer 2

如果装饰方法已经过验证，那么只调用它怎么样？如果愿意，可以传递validate方法的返回值：

class BaseClass(object):
    def getvalue(self):
        return True

    def validate(input_function):
        def wrapper(self, *args, **kwargs):
            self.validated = self.getvalue()
            if not self.validated:
                print "Not validated."
                return
            input_function(self, validated=self.validated, *args, **kwargs)
        return wrapper

    validate = staticmethod(validate)

class ExtendedClass1(BaseClass):
    @BaseClass.validate
    def do_some_work(self, validated=None):
        print "Things are validated if the method got this far.", validated

class ExtendedClass2(BaseClass):
    @BaseClass.validate
    def do_some_work(self, validated=None):
        print "Things are validated if the method got this far.", validated

class ExtendedClass3(BaseClass):
    def do_some_work(self):
        print "This one doesn't require validation."

work1 = ExtendedClass1()
work1.do_some_work()

work2 = ExtendedClass2()
work2.do_some_work()

work3 = ExtendedClass3()
work3.do_some_work()

这里的关键是将self添加到wrapper函数中。所发生的情况是，修饰函数没有绑定到实例（并成为方法），而是由修饰器返回的函数（在上面的示例中是wrapper）绑定到实例。因此，此函数将在调用时获得传入的self（实例）参数！重要的是要记住，@decorator所做的只是调用decorator传入您正在装饰的函数，然后用装饰器返回的内容替换您正在装饰的函数。在您的示例中，这是wrapper，对于类来说，这与装饰之前的原始函数没有区别。你知道吗

在上面的例子中，我显式地声明了self。如果我们没有，我们也可以从args中得到它：

def validate(input_function):
    def wrapper(*args, **kwargs):
        print "args[0] is now the instance (conventionally called 'self')", args[0]
        self = args[0]
        self.validated = self.getvalue()
        if not self.validated:
            print "Not validated."
            return
        input_function(validated=self.validated, *args, **kwargs)

还要注意，我们将一个额外的关键字参数传递给包装的方法，名为validated。这是完全可选的，您可以从示例中删除validated=self.validated和validated=None部分。你知道吗