On Fri, Apr 10, 2009 at 08:44:37PM +0200, Stefan Lesicnik wrote: > I am a relative newbie to python and OOP concepts and am trying to > work through wxpython. I've seen understanding classes is essential to > this and have been trying to work through them.
Welcome! If you're really new, wxpython may be a bit advanced, so if it feels like you're just not getting what's going on, you might want to step back a level and try simpler projects and work back up to this. > 1. I am not sure why / when you use the self. notation. I understand > that self refers to the instance you create, so you can have multiple > instances and the class knows which one you are talking about. > Why do they use self.Bind or similar and at other times use file = > (without the self) Inside the definition of a class method such as MenuExample.__init__() in your included code (and thank you, by the way, for including actual code to discuss!), if you assign to a variable such as file = wx.Menu() this is referring to a *local* variable "file" which will exist as long as the __init__() method is actually running (each time) and then get deleted when that function finishes running. It's a temporary variable, in other words. On the other hand, something like self.file = wx.Menu() would store this in an *instance* variable "self.file" which will exist as long as that object instance does, stored into the object itself so to speak. Calling a method like self.Bind(...) means to invoke the Bind method on this same object instance. If you wanted to call the Bind method on object foo, you'd say foo.Bind() so this is the same thing, just referring to the same object that's in the middle of its own __init__() call at the time. > 2. In the Bind( they use self.OnQuit which seems to call the function > OnQuit). Again, why is it self.OnQuit? Because it's not simply a function, it's a method of the class, and specifically you're asking the individual object "self" to perform its OnQuit action. > 3. def OnQuit(self, event): - where does event here come from and what > does it do with it? Here's one reason I said wxpython is pretty advanced. GUI code tends to be event-driven, so as the user triggers events such as clicking on buttons or typing keys, those events cause methods to be called in the objects controlling those on-screen widgets. So if, say, the user clicked a "quit" button, WX says that a button-press event occurred, and will call the OnQuit method here with information about the event in the object called "event". Your method could just ignore that parameter if you don't care about that, or you could examine it to see details as to what event led you to the OnQuit action. -- Steve Willoughby | Using billion-dollar satellites st...@alchemy.com | to hunt for Tupperware. _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
