__dict__.update() 是旧式的吗？答案

【问题标题】：Is __dict__.update() oldstyle?__dict__.update() 是旧式的吗？
【发布时间】：2011-10-19 13:31:17
【问题描述】：

我对新样式与旧样式属性的差异感到困惑。在这个例子中：

这段代码是否使用旧式方法来修改属性？

在Event()self.__dict__.update(kw)
我使用 getattr、getattr 还是 getattribute ？

为Dispatcher.dispatch_to_parent()

代码来自http://www.pygame.org/wiki/CommandDispatch?parent=CookBook

class Event(object):
    def __init__(self, name, kw={}):
        self.name = name
        self.__dict__.update(kw)
        self.dict = dict(kw)
        self.method_name = 'EVT_%s' % self.name

    def __repr__(self):
        return "<event>" % (self.name, self.dict)

class Dispatcher(object):
    def add(self, other):
        if isinstance(other, Dispatcher):
            other.parent = self
        else:
            raise ValueError("%s is not a Dispatcher" % other)

    def remove(self, other):
        if isinstance(other, Dispatcher):
            if other.parent is self:
                del other.parent
            else:
                raise ValueError("%s is not my child." % other)
        else:
            raise ValueError("%s is not a Dispatcher" % other)

    def dispatch(self, event):
        method = getattr(self, event.method_name, None)
        if method is not None: 
            return method(event)
        else:
            self.dispatch_to_parent(event)

    def dispatch_to_parent(self, event):
        parent = getattr(self, 'parent', None)
        if parent is not None:
            dispatch = getattr(parent, 'dispatch', None)
            if dispatch is not None: 
                return dispatch(event)

class Root(Dispatcher):
    def __init__(self):
        Dispatcher.__init__(self)
        self.focused_node = self

    def focus(self, node):
        if node is self.focused_node: return
        print 'focusing on', node
        self.focused_node.dispatch(Event('BLUR'))
        self.focused_node = node
        node.dispatch(Event('FOCUS'))

    def blur(self, node):
        self.focused_node = self
        node.dispatch(Event('BLUR'))

    def post(self, event_name, kw):
        event = Event(event_name, kw)
        return self.focused_node.dispatch(event)

if __name__ == "__main__":
    class Button(Dispatcher):
        def EVT_KeyDown(self, event):
            return self
    #create the root node, which is the receiver of all events.        
    r = Root()
    #create a button node
    b = Button()
    #add the button node to the application
    r.add(b)
    #give the button node focus, it will now receive events
    r.focus(b)
    #post a KeyDown event, which the button will receive
    print r.post('KeyDown')
    #post a Quit event, which the button will not receive. 
    #this event will be passed onto the button parent
    print r.post('Quit')
    #the return value of the post method is the node which handled the event

【问题讨论】：

这段代码中的所有类都是新样式类。不过，我不太确定你在问什么。
在老式类中，__dict__ 属性不可用...

标签： python pygame python-2.7 new-style-class

【解决方案1】：

您不应该直接更新实例字典，您将绕过自定义设置器。遍历键并执行 setattr。

【讨论】：

【解决方案2】：

def post(self, event_name, kw): 行中缺少 *

为了让你的函数能够接收一个字典作为参数，你需要在变量名前添加**：

def post(self, event_name, **kw):
    event = Event(event_name, kw)
    return self.focused_node.dispatch(event)

【讨论】：