Python Sales Management By Nishad TK

import re
class shop:
    def __init__(self):
        self.stock=[]
        self.sales=0
        self.purchase=0

        
    def addStock(self):
        name=raw_input("Enter the product name")
        while not re.match(re.compile(r'[a-zA-Z]+'),name):
                       name=raw_input("Invalid product name , Please try again")
        price=raw_input("Enter the product price")
        while not re.match(re.compile(r'[0-9]+'),price):
                       price=raw_input("Invalid product price , Please try again")
        quantity=raw_input("Enter the product quantity")
        while not re.match(re.compile(r'[0-9]+'),quantity):
                       quantity=raw_input("Invalid product quantity , Please try again")
        ele=[name,price,quantity]
        self.stock.append(ele)

        
    def sales(self,product):
        for i in range(0,len(self.stock)):
            if re.match(product[0],self.stock[i][0]):
                self.stock[i][2]=int(self.stock[i][0])-int(product[2])
                flag=True
        if flag!=True:
            return False

        
    def purchase(self,product):
        for i in range(0,len(self.stock)):
            if re.match(product[0],self.stock[i][0]):
                self.stock[i][2]=int(self.stock[i][0])+int(product[2])
                flag=True
        if flag!=True:
            self.stock.append(product)


class customer:
    consumerno=0
    def __init__():
        cid=consumerno
        consumerno+=1
        name=raw_input("Enter the Consumer name")
        while not re.match(re.compile(r'[a-zA-Z]+'),name):
            name=raw_input("Invalid name , Please try again")
        phone=raw_input("Enter the consumer phone")
        while not re.match(re.compile(r'[0-9]+'),phone):
            phone=raw_input("Invalid  phone , Please try again")
        self.purchases=[]
        self.phone=phone
        self.name=name
                       
    def purchase(self,product):
        self.purchases.append(product)

while True:
    menu="""Choose an operation
    1.Add Stock
    2.Create Consumer
    3.Purchase
    4.Sell
    5.View Consumers
    6.View Purchases
    7.View Sales
    8.Exit\n"""
    ch=str(raw_input(menu))
    while not re.match(re.compile(r'[1-8]'),ch):
        ch=str(raw_input("Invalid choice , Try Again:"))
    if ch=='8':
        break
    else:
        switch(ch)