Python创建和遍历一个简单的菜单

Question

我正在创建我的第一个Python项目。我正在研究的是一个简单的基于文本的度量到标准（反之亦然）的转换程序。我不是在寻找代码，因为我想自己解决这个问题。但是，我在遍历菜单时遇到了一个问题。例如，有3个菜单:主菜单，公制菜单和标准菜单。程序打开到主菜单。在主菜单上，用户可以选择导航到metric菜单，standard菜单或退出程序。如果用户希望能够从度量或标准菜单返回到主菜单，最好的方法是什么？我试过while循环和if/elif。然而，我的代码似乎变得非常臃肿和复杂。有人能给我一些关于在Python中创建和遍历文本菜单的建议吗？

Answer 1

因为您说您是Python的新手，所以在第一次构造对象时调用类的__init_()方法。你可以在这里阅读关于类的文档（跳到9.3）。

我不知道这会有多大的效率，但是您可以使用一个存储同一类的其他对象的类:

class Menu:
    def __init__(self, content, short_view, submenus = None):
        self.content = content
        self.short_view = short_view
        if submenus != None:
            self.choices = dict(enumerate(submenus, 1))
            for sub in submenus:
                sub.parent = self
        else:
            self.choices = {}


subsub1 = Menu("this is subsub1 content", "this goes to subsub1")
subsub2 = Menu("this is subsub2 content", "this goes to subsub2")
subsub3 = Menu("this is subsub3 content", "this goes to subsub3")

sub1 = Menu("this is the first sub menu content", "this goes to sub1", [subsub1, subsub2, subsub3])
sub2 = Menu("this is the second sub menu content", "this goes to sub2")

main = Menu("this is the main menu content", "this goes to main, but will never be used", [sub1, sub2])
main.parent = main

current_menu = main
while True:
    print(current_menu.content)
    print("\n".join([f"[{num}] {current_menu.choices[num].short_view}" for num in current_menu.choices]))
    inpt = input("Choice: ")
    if inpt == "exit":
        break
    elif inpt == "back":
        current_menu = current_menu.parent
    else:
        current_menu = current_menu.choices[int(inpt)]

用法（在shell中）:

this is the main menu content
[1] this goes to sub1
[2] this goes to sub2
Choice: 1
this is the first sub menu content
[1] this goes to subsub1
[2] this goes to subsub2
[3] this goes to subsub3
Choice: back
this is the main menu content
[1] this goes to sub1
[2] this goes to sub2
Choice: exit
>>>

Answer 2

您可以尝试如下所示:

import sys
import os

def switch():
    clear = lambda: os.system('cls')
    clear()
    s = 0
    while s != 5:
        s = int(input('1)Metric 2)Standard 3)Exit\n'))
        if s == 1:
            clear = lambda: os.system('cls')
            clear()
            metric()
        elif s == 2:
            clear = lambda: os.system('cls')
            clear()
            standard()
        elif s == 3:
            clear = lambda: os.system('cls')
            clear()
            exit()
        else:
            print('Out of range.')

def metric():
    '''Your code here'''
    s = int(input('0)Back\n'))
    if s == 0:
        switch()
    else:
        print('Out of range.')
    
def standard():
    '''Your code here'''
    s = int(input('0)Back\n'))
    if s == 0:
        switch()
    else:
        print('Out of range.')
    

switch()