我如何使班级互相交谈？

Question

Here is the situation

class App(wx.Frame):
    def __init__(self,parent,id=-1,title='Test App'):
        wx.Frame.__init__(self,parent,id,title,size=((1050,690)))

        self.mode = 'Test'


class SetModes:
    def __init__(self):
        self.GetModes = App(None,-1)

        self.appmode = ''

    def SetMode(self):
        self.appmode = self.GetModes.mode

Now this is just an example script because I already know this won't work but it shows what im essentially trying to do. Let me clarify:

I want to get and set some variables from the app class. I want to be able to do this from my 'SetModes' class. Problem is I can't make a instance of it because I can't assign a parent to the instance so the self.GetModes method doesn't work, It tells me either the instance can't 'NOT' have a parent, So does this mean I can't create an instance of my App Class if all I want to do is use some of it's variables and functions??.

So How do I get this to work. Can I have a class communicate with a class that requires a parent?

Answer 1

I think part of your problem is that frames need to be initialized from inside a wx.App instance and then the MainLoop() must be called (see this tutorial . Note how the frame has a parent None ).

After that, a solution like jdi's will work. However, I still don't like using references if I can avoid it. For a parent calling functions on an immediate child, it's ok but my own personal rule is that my classes cannot see any objects they do not directly own (ie no knowledge about children of children).

I'm a big fan of PubSub for communicating between unrelated classes. Unlike wx.Event objects, there is no need for any heirarchical relationship. Unlike the reference solution put forth by jdi, there is no need for classes to have any knowledge at all about each other's structures.

What it comes down to is, in your application, can a SetModes instance ever exist without an App instance? If no, can you maybe incorporate SetModes ' logic into App ? If yes, then coding SetModes to explicitly deal with App is bad design.

Using PubSub , you send a request message from SetModes . App sees the message and can then send a response message, which is seen by SetModes . Completely separate, completely asynchronous. SetModes doesn't need to know anything about App , just the message formats.

Answer 2

Just because the wx.Frame requires a parent, doesn't mean you can't assign a reference to it in another unassociated class. Just parent your App instance to something as you would do normally, but pass the reference over to your SetModes:

app = App(parent)
setModes = SetModes()
setModes.GetModes = app

This comes down to a design issue with your program. Widgets need parents.