如何在urwid中创建嵌套列表框？

Question

是否可以将ListBoxes放在SimpleListWalkers中？我正在尝试创建嵌套的ListBoxes，但是我有以下错误：

AttributeError: 'MyListBox' object has no attribute 'rows'

import urwid

class MyListBox(urwid.ListBox):
    def focus_next(self):
        try: 
            self.body.set_focus(self.body.get_next(self.body.get_focus()[1])[1])
        except:
            pass
    def focus_previous(self):
        try: 
            self.body.set_focus(self.body.get_prev(self.body.get_focus()[1])[1])
        except:
            pass            

def handle_input(event):
    frame.header.set_text("key pressed %s" % event)
    if event == "q":
        raise urwid.ExitMainLoop
    elif event == "up":
        lb.focus_previous()
    elif event == "down" :
        lb.focus_next()        

widgets   = [urwid.AttrMap(urwid.Text(str(x)),None,"focus") for x in xrange(3)]
nested    = [urwid.AttrMap(urwid.Text(str(x)+"_sous"),None,"focus") for x in xrange(3)]
nested_lb = MyListBox(urwid.SimpleListWalker(nested))
lb        = MyListBox(urwid.SimpleListWalker(widgets+[nested_lb]))
frame     = urwid.Frame(lb,header=urwid.Text("Header"))
palette   = [("focus","dark cyan","white")]
loop      = urwid.MainLoop(frame,palette,unhandled_input = handle_input)
loop.screen.set_terminal_properties(colors=256)
loop.run()

Answer 1

根据手册的说法，ListBox是一个盒子小部件，里面包含流小部件。

小部件类型(框、流和固定)之间的区别在于它们的大小的计算方法。详细信息在上述链接中进行了描述。简而言之：ListBox从它的容器中得知它的大小，但要求它的孩子自己计算高度。由于另一个ListBox在里面，它不能提供这个值(没有rows方法)。

解决方案是将内部ListBox封装在BoxAdapter中，从而使box小部件看起来和行为类似于flow小部件：

...
widgets   = [urwid.AttrMap(urwid.Text(str(x)),None,"focus") for x in xrange(3)]
nested    = [urwid.AttrMap(urwid.Text(str(x)+"_sous"),None,"focus") for x in xrange(3)]
nested_lb = MyListBox(urwid.SimpleListWalker(nested))
lb        = MyListBox(urwid.SimpleListWalker(widgets+[urwid.BoxAdapter(nested_lb, 10)]))
...