Python類繼承函數和從子項傳遞參數

Question

class BaseMenu(object): 
    def display(self): 
     header = "FooBar YO" 
     term = getTerminalSize() 
     #sys.stdout.write("\x1b[2J\x1b[H") 
     print header.center(term, '*') 
     #print sub_menu.center(term, '+') 
     print "Please choose which option:" 
     for i in options: 
      print(
       str(options.index(i)+1) + ") " 
      ) 

class Servers(BaseMenu): 
    def __init__(self): 
     #super(Servers, self).__init__("server") 
     pass 

    def list_foo(self): 
     pass 
    def list_bar(self): 
     pass 
    options = (
     list_foo, 
     list_bar 
     ) 

試圖製作一系列以Main Menu - > Servers子菜單開始的文本菜單。當Servers（）從BaseClass繼承display（）時，如何使Servers（）類中包含的繼承函數display（）接收選項tuple和sub_menu =「Server Menu」字符串？

Answer 1

可以在display功能使用self.options和self.sub_menu，但是爲什麼你在BaseMenu類一無所知options或sub_menu引用它們呢？

第二個問題，您將"server"參數傳遞給__init__不帶任何參數的類，因此您需要添加該參數。

如果你打算永遠不會實例化一個BaseMenu對象，那麼它就是一個抽象基類（或ABC）。你可以把它定義爲這樣使用蟒蛇abc模塊以確保繼承類定義的屬性，你期待：

import abc 

class BaseMenu(object): 
    __metaclass__ = abc.ABCMeta #indicate that this is an ABC 

    @abc.abstractproperty # prevent derived classes that don't have options 
    def options(self): 
     pass 

    @abc.abstractproperty 
    def sub_menu(self): 
     pass 

    def __init__(self, menu_name): # takes the menu name as an argument ("server") 
     self.menu_name = menu_name 

    def display(self): 
     header = "FooBar YO" 
     term = getTerminalSize() 
     print header.center(term, '*') 
     print self.sub_menu.center(term, '+') # NOTE self.sub_menu 
     print "Please choose which option:" 
     for i in self.options: # NOTE self.options 
      print(self.options.index(i)+1 + ") ") 

如果任何類試圖從BaseMenu繼承而不定義options和sub_menu它會導致TypeError像下面是實例：

TypeError: Can't instantiate abstract class Servers with abstract methods options 

Answer 2

我不知道我完全得到你在這裏問的，所以告訴我，這是怎麼回事？

class BaseMenu(object): 

    # Added some attributes here: 
    menuName = "" 
    options =() 

    def __init__(self, menu_name, opt): 
     self.menuName = menu_name # = "Servers Menu" when instantiated as Server 
     self.options = opt   # the passed when instantiated as Server 

    def display(self): 

     # Use self.menuName and self.options here 

     #... 
     for i in self.options: 
      print(
       str(self.options.index(i)+1) + ") " + str(i) 
      ) 

class Servers(BaseMenu): 

    def list_foo(self): 
     pass 
    def list_bar(self): 
     pass 

    options = (
     list_foo, 
     list_bar 
     ) 

    def __init__(self, menu_name): 
     super(Servers, self).__init__(menu_name, self.options) 

實例化Servers類是這樣的：

servers = Servers("Servers Menu") 
servers.display() 

輸出：

1) <function list_foo at 0x29e06e0> 
2) <function list_bar at 0x29e0758> 

難道合適？