Command prompt messed up after running a Python program

问题

The code below creates a layout and displays some text in the layout. Next the layout is displayed on the console screen using the raw display module from the Urwid library. (More information on my complete project can be gleaned from questions at Required widgets for displaying a 1D console application and Using Urwid to create a 2D console application.

My skype help request being here. I can run the code to display the relevant information. On pressing F8 the code asks a dialog on screen if to exit. On pressing the 'y' key, the application ends. But right after that the commmand prompt is messed up. I am not able to write anything at the command prompt. Pressing the Enter button only repeats the command prompt as follows:

[gehna@localhost urwidFormBrowser]$ [gehna@localhost urwidFormBrowser]$ [gehna@localhost urwidFormBrowser]$

The code is:

#!/usr/bin/env python

import sys
sys.path.append('./lib')
import os
from pprint import pprint
import random
import urwid
ui = urwid.raw_display.Screen()

class FormDisplay(object):

    def __init__(self):
        global ui
        #self.ui = urwid.raw_display.Screen()
        self.ui = ui
        self.palette = self.ui.register_palette([
            ('Field', 'dark green, bold', 'black'), # information fields, Search: etc.
            ('Info', 'dark green', 'black'), # information in fields
            ('Bg', 'black', 'black'), # screen background
            ('InfoFooterText', 'white', 'dark blue'), # footer text
            ('InfoFooterHotkey', 'dark cyan, bold', 'dark blue'), # hotkeys in footer text
            ('InfoFooter', 'black', 'dark blue'),  # footer background
            ('InfoHeaderText', 'white, bold', 'dark blue'), # header text
            ('InfoHeader', 'black', 'dark blue'), # header background
            ('BigText', RandomColor(), 'black'), # main menu banner text
            ('GeneralInfo', 'brown', 'black'), # main menu text
            ('LastModifiedField', 'dark cyan, bold', 'black'), # Last modified:
            ('LastModifiedDate', 'dark cyan', 'black'), # info in Last modified:
            ('PopupMessageText', 'black', 'dark cyan'), # popup message text
            ('PopupMessageBg', 'black', 'dark cyan'), # popup message background
            ('SearchBoxHeaderText', 'light gray, bold', 'dark cyan'), # field names in the search box
            ('SearchBoxHeaderBg', 'black', 'dark cyan'), # field name background in the search box
            ('OnFocusBg', 'white', 'dark magenta') # background when a widget is focused
           ])
    urwid.set_encoding('utf8')

    def main(self):
        global ui
        #self.view = ui.run_wrapper(formLayout)
        self.ui.start()
        self.view = formLayout()
        self.exit_view = formLayoutExit()
        self.loop = urwid.MainLoop(self.view, self.palette, unhandled_input=self.unhandled_input)
        self.loop.widget = self.view
        self.loop.run()

    def unhandled_input(self, key):
        if key == 'f8':
            self.loop.widget = self.exit_view
            return True
        if self.loop.widget != self.exit_view:
            return
        if key in ('y', 'Y'):
            raise urwid.ExitMainLoop()
        if key in ('n', 'N'):
            self.loop.widget = self.view
            return True

def formLayout():
    global ui
    text1 = urwid.Text("Urwid 3DS Application program - F8 exits.")
    text2 = urwid.Text("One mission accomplished")
    textH = urwid.Text("topmost Pile text")
    cols = urwid.Columns([text1,text2])
    pile = urwid.Pile([textH,cols])
    fill = urwid.Filler(pile)

    textT  = urwid.Text("Display")

    textSH = urwid.Text("Pile text in Frame")
    textF = urwid.Text("Good progress !")

    frame = urwid.Frame(fill,header=urwid.Pile([textT,textSH]),footer=textF)
    dim = ui.get_cols_rows()
    #ui is treated as global handle for all functions, either belonging
    #to any class or standalone functions such as formLayout
    #need to check if screen has been started
    if not ui._started:
        print("Screen has not been started, so no use of rendering.Thus return :-( ")
        return

    ui.draw_screen(dim, frame.render(dim, True))
    return frame


def formLayoutExit():
    exit = urwid.BigText(('exit'," Quit? "), urwid.font.HalfBlock5x4Font())
    exit = urwid.Overlay(exit, formLayout(), 'center', None, 'middle', None)
    return exit

def RandomColor():
    '''Pick a random color for the main menu text'''
    listOfColors = ['dark red', 'dark green', 'brown', 'dark blue',
                    'dark magenta', 'dark cyan', 'light gray',
                    'dark gray', 'light red', 'light green', 'yellow',
                    'light blue', 'light magenta', 'light cyan', 'default']
    color = listOfColors[random.randint(0, 14)]
    return color

def main():
    #global ui
    form = FormDisplay()
    form.main()

########################################
##### MAIN ENTRY POINT
########################################
if __name__ == '__main__':
    main()

I suspect the behaviour shown after the application exits has got to do something with return calls of the functions FormDisplay, formlayout and formlayoutExit. How can I fix this problem?

回答1:

make sure to use sys.exit(retCode) at the completion of your execution, and this problem should not happen

回答2:

If there is an error/exception your program is supposed to undo the changes to the terminal which were done during the initialization of curses. If you don't want to do that, there is a wrapper function provided. Please check the documentation.

In your case, instead of calling main directly you can call through the wrapper.

curses.wrapper(main)

来源：https://stackoverflow.com/questions/17910768/command-prompt-messed-up-after-running-a-python-program