python输出重定向

import wx
import sys
class Frame(wx.Frame):
    def __init__(self,parent,id,title):
        print("Frame __init__")
        wx.Frame.__init__(self, parent, id, title)
class App(wx.App):
    def __init__(self, redirect=True, filename=None):
        print ("App __init__")
        wx.App.__init__(self, redirect, filename)
    def OnInit(self):
        print("OnInit")   #输出到stdout
        self.frame = Frame(parent=None, id=-1, title="Startup")    #创建框架
        self.frame.Show()
        self.SetTopWindow(self.frame)
        print("A pretend error message")  #输出到stderr
        return True
    def OnExit(self):
        print ("OnExit")
        return True
if __name__ == "__main__":
    app = App(redirect=True,filename="output.txt")  # 1 文本重定向从这开始  
    print ("before MainLoop")
    app.MainLoop()      # 2 进入主事件循环   
    print ("after MainLoop")