menu while loop

[Gribouillis]

I suggest to insert the various menus in a collection (here a dictionary named 'menus'). This allows to refer to them more easily, add more of them etc.

Another useful feature is a registering system to register actions to do when the user makes a choice. Try to play with the following extensible code outline to see if you like it

import re

class Menu:
    def __init__(self, name, value):
        self.name = name
        self.value = value
        self.options = [s[1:-1] for s in re.findall(r'\[[^\]]*\]', value)]
        
    def __str__(self):
        return(self.value)

menus = {}

menus['main'] = Menu('main', """\
[1] Products
[2] Clients
[3] Display
[4] Report
[0] Exit the program.""")
 
menus['products'] = Menu('products', """\
[1] Add new product
[2] Product update
[3] Delete product
[4] Go back to main page
[0] Exit the program.""")
 
menus['clients'] = Menu('clients', """\
[1] Add new client
[2] Client update
[3] Delete client
[4] Go back to main page
[0] Exit the program.""")
 
 
menus['display'] = Menu('display', """\
[1] Search list of: 
[2] Search a: 
[4] Go back to main page
[0] Exit the program.""")
 
menus['reports'] = Menu('reports', """\
[1] Average age of clients: 
[2] The average price of the products 
[4] Return to the main menu
[0] Exit the program.""")

def ask_option(menu):
    while True:
        print(menu)
        opt = input('Please select an option: ')
        if opt in menu.options:
            try:
                return int(opt)
            except ValueError:
                return opt
        else:
            print(f'Invalid option, please choose one of {menu.options}')
            
registered = {}

def register(name, opt):
    def decorator(func):
        registered[(name, opt)] = func
        return func
    return decorator

@register('main', 1)
def main_choose_products(menu, opt):
    return menus['products']

@register('main', 2)
def main_choose_clients(menu, opt):
    return menus['clients']

@register('main', 3)
def main_choose_display(menu, opt):
    return menus['display']

@register('main', 4)
def main_choose_reports(menu, opt):
    return menus['reports']

@register('main', 0)
@register('products', 0)
@register('clients', 0)
@register('display', 0)
@register('reports', 0)
def all_choose_exit(menu, opt):
    return None

if __name__ == '__main__':
    menu = menus['main']
    while menu:
        opt = ask_option(menu)
        func = registered.get((menu.name, opt), None)
        if func:
            menu = func(menu, opt)
        else:
            menu = menus['main']