python中的main函数调用失败

Question

我编写了以下代码来创建布局并在布局中显示一些文本。接下来，使用 urwid 库中的原始显示模块将布局显示在控制台屏幕上。 但是运行代码失败，因为它没有找到我在类中单独编写的函数 ma​​in。

运行时的错误代码是：

Traceback (most recent call last):  
  File "./yamlUrwidUIPhase5.py", line 89, in <module>
    main()  
  File "./yamlUrwidUIPhase5.py", line 83, in main
    FormDisplay().main()  
AttributeError: 'NoneType' object has no attribute 'main'

代码：

import sys  
sys.path.append('./lib')  
import os  
from pprint import pprint  
import random  
import urwid  

def formLayout():
    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.draw_screen(dim, frame.render(dim, True))  

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 FormDisplay():
    import urwid.raw_display
    ui = urwid.raw_display.Screen()
    palette = 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):
    #self.view = ui.run_wrapper(formLayout)
    self.view = formLayout()
    ui.start()
    self.loop = urwid.MainLoop(self.view, self.palette, unhandled_input=self.unhandled_input)
    self.loop.run()

def unhandled_input(self, key):
    if key == 'f8':
        quit()
        return
def main():
    global ui

    FormDisplay().main()

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

Answer 1

您的代码中的FormDisplay 不是一个类而是一个函数，这样的东西会更合适。顺便说一句，我建议阅读此文档http://docs.python.org/2/tutorial/classes.html

import urwid.raw_display

class FormDisplay(object):

    def __init__(self):
        self.ui = urwid.raw_display.Screen()
        self.palette = 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
       ])

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

if __name__ == "__main__":
    form = FormDisplay()
    form.main()

Answer 2

我没有看到任何单独的课程。但根据您的代码，FormDisplay 是一个不返回任何内容的函数。 FormDisplay().main() 等于 None.main()。