python wnck在pdb.set_trace()之后才返回任何数据

Question

在Ubuntu Linux / Gnome上，我尝试使用python的wnck绑定来获取所有打开的窗口的列表。

我的代码如下所示：

#! /usr/bin/python

from pprint import pprint
import wnck

screen = wnck.screen_get_default()

pprint(screen.get_windows())

import pdb ; pdb.set_trace()

pprint(screen.get_windows())

输出如下所示：

** (windowlist.py:4501): WARNING **: Trying to register gtype 'WnckWindowState' as enum when in fact it is of type 'GFlags'

** (windowlist.py:4501): WARNING **: Trying to register gtype 'WnckWindowActions' as enum when in fact it is of type 'GFlags'

** (windowlist.py:4501): WARNING **: Trying to register gtype 'WnckWindowMoveResizeMask' as enum when in fact it is of type 'GFlags'
[]
> /home/rory/personal/diriu/windowlist.py(12)<module>()
-> pprint(screen.get_windows())
(Pdb) c
[<wnck.Window object at 0xb61db0cc (WnckWindow at 0x992c000)>,
 <wnck.Window object at 0xb61db0f4 (WnckWindow at 0x992c0a8)>,
 <wnck.Window object at 0xb61db11c (WnckWindow at 0x992c150)>,
 <wnck.Window object at 0xb61db144 (WnckWindow at 0x992c1f8)>,
 <wnck.Window object at 0xb61db16c (WnckWindow at 0x992c2a0)>,
 <wnck.Window object at 0xb61db194 (WnckWindow at 0x992c348)>,
 <wnck.Window object at 0xb61db1bc (WnckWindow at 0x992c3f0)>,
 <wnck.Window object at 0xb61db1e4 (WnckWindow at 0x992c498)>,
 <wnck.Window object at 0xb61db20c (WnckWindow at 0x992c540)>,
 <wnck.Window object at 0xb61db234 (WnckWindow at 0x992c5e8)>,
 <wnck.Window object at 0xb61db25c (WnckWindow at 0x992c690)>,
 <wnck.Window object at 0xb61db284 (WnckWindow at 0x992c738)>]

第一个get_windows()调用返回[]，一个空列表。第二个get_windows()调用返回一个打开的窗口列表。在pdb中，我只按c继续，什么也不做(在pdb中)。

如果我注释掉pdb，两个get_windows()调用都会返回[]。如果我在pdb之前多次重复get_windows()调用，则什么也没有。如果我在pdb之后多次重复get_windows()调用，我会不断得到一个完整的列表。

为什么此调用仅在空pdb之后才起作用？如何在没有pdb的情况下使其工作？

Answer 1

文件so-wnck.py (来自How might I grab all windows with a certain word in their titles?)

import pygtk
pygtk.require('2.0')
import gtk
import wnck

screen = wnck.screen_get_default()
while gtk.events_pending():
    gtk.main_iteration()

windows = screen.get_windows()
print (windows)

python so-wnck.py

** (so-wnck.py:2367): WARNING **: Trying to register gtype 'WnckWindowState' as enum when in fact it is of type 'GFlags'

** (so-wnck.py:2367): WARNING **: Trying to register gtype 'WnckWindowActions' as enum when in fact it is of type 'GFlags'

** (so-wnck.py:2367): WARNING **: Trying to register gtype 'WnckWindowMoveResizeMask' as enum when in fact it is of type 'GFlags'
[<wnck.Window object at 0xb7566694 (WnckWindow at 0x97c51f8)>,
 <wnck.Window object at 0xb75666bc (WnckWindow at 0x97c52a0)>, 
 <wnck.Window object at 0xb75666e4 (WnckWindow at 0x97c5348)>, 
 <wnck.Window object at 0xb756670c (WnckWindow at 0x97c53f0)>, 
 <wnck.Window object at 0xb7566734 (WnckWindow at 0x97c5498)>,
 <wnck.Window object at 0xb756675c (WnckWindow at 0x97c5540)>, 
 <wnck.Window object at 0xb7566784 (WnckWindow at 0x97c55e8)>]

Answer 2

我不使用wnck，但我认为在pdb的情况下，两次调用get_window之间的时间足以初始化窗口列表。在调用get_window之前，尝试使用带有一些延迟的睡眠。