[Urwid] How do you use SimpleListWalker?

[Ian Ward]

Corrected example below.

Ian Ward wrote:
> What you describe should work, but I'm not a fan of mixing such
> different interfaces in the same class.
> 
> I would use a slightly modified SimpleListWalker class for storing your
> list of conversations, and give each of your conversation objects a
> button object (or whatever widget you like) stored as ".widget"

class ThreadedMessageWalker(SimpleListWalker):

    def get_focus(self):
        if len(self)==0: return None, None
        return self[self.focus].widget, self.focus

    def get_next(self, start_from):
        pos = start_from+1
        if len(self) <= pos: return None, None
        return self[pos].widget, pos

    def get_prev(self, start_from):
        pos = start_from-1
        if pos < 0: return None, None
        return self[pos].widget, pos

> 
> This way your list updates automatically, and the ListBox only sees the
> widgets.
> 
> Ian