Chapter 12, Problem 4PE

Program Plan Intro

Tracking conference attendees

Program plan:

• In a file “atmmanager.py”,
  • Create a class “ATMAp” that calls account information from JSON file and modifies it according to the commands given through an interface class.
    • Define the function “_init_()”  to create a list of users and manage the account information.
    • Define the “run()” function  to execute the transaction according to user input.
    • Define the function “screen_1()” to return the user input.
    • Define the function “screen_2()” to process the transaction according to the user input.
    • Define the function “get_User()” to return the user with the given user id.
    • Define the function “send_Money()” to  move the amount from one user to another. There are two types of accounts are used; “Checking” and “Savings”.
    • Define the function “_updateAccounts()” to update the amount in output file whenever the transaction has occurred.
    • Define the function “verify()” to check whether the userid and pin given by the user is matched with the saved userid and pin.
  • Create a class “User”,
    • Define the function “_init_()” method to assign the initial values.
    • Define the function “check_Balances()” to return the amount of balance in checking and savings account.
    • Define the function “exchange_Cash()” to deposit or withdraw amount fro checking or savings account.
    • Define the function “transfer_Money()” to transfer the amount between checking and savings account.
    • Define the function “getID()” to return the user id.
    • Define the function “getPIN()” to return the pin.
• In the file “textatm.py”,
  • Create a class “TextInterface”,
    • Define “_init_()” method to assign initial values.
    • Define the function “get_UserInput()” to return the user inputs.
    • Define the function “choose_Transaction()”  to select the type of transaction.
    • Define the function “display_Balanace()”  to print the amount in savings and checking accounts.
    • Define the function “withdraw_Cash()” to return the withdraw amount and account type.
    • Define the function “getTransferInfo()” to return the information of amount transfer between checking and savings account.
    • Define the function “getSendInfo()” to return the information of receiver amount transfer.
    • Define the function “close()”  to exit the transaction.
• In a file “atm.py”,
  • Import necessary packages.
  • Define the “main()” function,
    • All the interface class “TextInterface”.
    • Call the “ATMAp” class functions with the argument of file and interface.
  • Call the “main()” function.

Program Description Answer

This Python program is to keep track of conference attendees.

Explanation of Solution

Program:

File name: “atmmanager.py”

#Import package

import json

#Create a class

class ATMAp:

    #Define the function

    def __init__(self, account_file, interface):

        #Open the file

        with open(account_file) as fi:

            #Serialize the object as a json stream

            data = json.load(fi)

        #Create a list of users

        self.users = []

        '''Create for loop to iterate key, value pairs till the list of tuples'''

        for key,value in data['users'].items():

            #Assign the value

            usr = User(value["userid"], value["pin"],value["checkin"],value["saving"], value["name"])

            #Append to the list

            self.users.append(usr)

        #Assign the value

        self.interface = interface

        #Call the run()

        self.run()

    #Define the run() function

    def run(self):

        #Execute while loop

        while not self.interface.close():

            #Call the functions

            self.screen_1()

            self.screen_2()

    #Define the function

    def screen_1(self):

        #Assign the values

        user_id = None

        pin = None

        #Execute while loop

        while not self.verify(user_id, pin):

            #Make simultaneous assignment

            user_id, pin = self.interface.get_UserInput()

        #Assign the value return from get_USer()

        self.user = self.get_User(user_id)

    #Define the function

    def screen_2(self):

        #Assign the value

        terminate = self.interface.close()

        #Execute while loop

        while not terminate:

            #Make simultaneous assignment

            checkin, saving = self.user.check_Balances()

            #Assign the value

            tran_type = self.interface.choose_Transaction()

            #Call the function

            self.__updateAccounts()

            #Execute the condition

            if tran_type[0] == "C":

                #Call the function

                self.interface.display_Balance(checkin, saving)

            #Execute the condition

            elif tran_type[0] == "W":

                #Make simultaneous assignment

                value, account_type = self.interface.withdraw_Cash()

                #Call the function

                self.user.exchange_Cash(value, account_type)

            #Execute the condition

            elif tran_type[0] == "T":

                #Make simultaneous assignment

                inaccount, outaccount, value = self.interface.getTransferInfo()

                #Call the function

                self.user.transfer_Money(inaccount, outaccount, value)

            #Execute the condition

            elif tran_type[0] == "S":

                #Make the assignment

                recipient, type_sender, type_recipient, value = self.interface.getSendInfo()

                #Assign the value return from get_User()

                recipient = self.get_User(recipient)

                #Call the function

                self.send_Money(self.user, recipient, value, type_sender, type_recipient)

            #Execute the condition

            elif tran_type[0] == "Q":

                #Call the function

                self.user.exchangeCash(-100, "Checking")

            #Execute the condition

            elif tran_type[0] == "E":

                #Call the unction

                self.__updateAccounts()

                #Assign the boolean value

                terminate = True

    #Define the function

    def get_User(self, userid):

        #Create for loop

        for user in self.users:

            #Check the condition

            if userid == user.getID():

                #Return the user object for the given userid

                return user

    #Define the function

    def send_Money(self, sender, recipient, value, type_sender, type_recipient):

        #Assign the values return from check_Balances()

        checking, savings = sender.check_Balances()

        checking, savings = recipient.check_Balances()

        #Call the functions

        sender.exchange_Cash(-value, type_sender)

        recipient.exchange_Cash(value, type_recipient)

    #Define the function

    def __updateAccounts(self):

        #Create dictionary

        data = {}

        #Assign empty dictionary

        data['users'] = {}

        #Create for loop

        for usr in self.users:

            #Assign the values

            json_str = (vars(usr))

            user_id = usr.getID()

            #Assign the value

            data['users'][user_id] = json_str

        #Open the output file in write mode

        with open('new_atmusers.json', 'w') as f:

            #Serialize the objecct as a json stream

            json.dump(data, f, indent=4)

    #Define the function

    def verify(self, user_id, pin):

        #Create for loop

        for usr in self.users:

            #Execute the condition

            if (usr.getID() == user_id) and (usr.getPIN() == pin):

                #Return boolean value

                return True

        #Otherwise

        else:

            #Return boolean value

            return False

#Create a class

class User:

    #Define _init_() method

    def __init__(self, userid, pin, checkin, saving, name):

        #Assign initial values

        self.userid = userid

        self.pin = pin

        self.checkin = float(checkin)

        self.saving = float(saving)

        self.name = name

    #Define the function

    def check_Balances(self):

        #Return two values

        return self.checkin, self.saving

    #Define the function

    def exchange_Cash(self, value, inaccount):

        #Check the condition

        if inaccount[0] == "C":

            #Assign the value

            self.checkin = round(self.checkin + value, 2)

        else:

            #Assign the value

            self.saving = round(self.saving + value, 2)

    #Define the function

    def transfer_Money(self, inaccount, outaccount, value):

        #Check the condition

        if inaccount[0] == "C":

            #Assign the values

            self.checkin = self.checkin + value

            self.saving = self.saving - value

        #Otherwise

        else:

            #Assign the values

            self.checkin = self.checkin - value

            self.saving = self.saving + value

    #Define the function

    def getID(self):

        """Returns userid"""

        #Return the value

        return self.userid

    #Define the function

    def getPIN(self):

        #Return the value

        return self.pin

File name: “textatm.py”

#Create a class

class TextInterface:

    #Define the function

    def __init__(self):

        #Assign boolean value

        self.active = True

        #Print the string

        print("Welcome to the ATM")

    #Define the function

    def get_UserInput(self):

        #Get user inputs

        a = input("Username >> ")

        b = input("Pin >> ")

        #Return the values

        return a, b

    #Define the function

    def choose_Transaction(self):

        #Display user balance

        #Assign the value

        tran = "xxx"

        #Execute the loop

        while tran[0] != ("C" or "W" or "T" or "S" or "E" or "Q"):

            #Get the choice

            tran = input('Please select a transaction from the approved list. "Check Balance", \n "Withdraw/Deposit Cash", "Transfer Money", "Send Money", "Exit", "Quick Cash $100 >> ')

            #Check the condition

            if tran[0] != "E":                   

                #Return the choice

                return tran

            else:

                #Assign boolean value

                self.active = False

                #Return the choice

                return tran

    #Define the function

    def display_Balance(self, checking, savings):

        #Print savings and checking

        print("Checking: {0}    Savings: {1}".format(checking, savings))

    #Define the function

    def withdraw_Cash(self):

        #Print the string

        print("This function will withdraw or deposit cash.")

        #Get the values

        value = eval(input("Enter the amount to deposit/withdraw? Enter negative value to withdraw. >> "))

        account = input("Checking or Savings account? >> ")

        #Print the string

        print("Transaction is complete.\n")

        #Retuen the values

        return value, account

    #Define the function

    def getTransferInfo(self):

        #Get the inputs

        outaccount = input("Select account to withdraw money from: >> ")

        inaccount = input("Select account to deposit money in: >> ")

        value = eval(input("How much would you like to move?"))

        #Print the string

        print("Transaction is complete.\n")

        #Return the values

        return inaccount, outaccount, value

    #Define the function

    def getSendInfo(self):

        #Get the inputs

        recipient = input("Recipient userid")

        type_sender = input("Sender: Checking or Savings?  >> ")

        type_recipient = input("Recipient: Checking or Savings?  >> ")

        value = eval(input("How much to send? >> "))

        #Print the string

        print("Transaction is complete.\n")

        #Return the values

        return recipient, type_sender, type_recipient, value

    #Define the function

    def close(self):

        #Execute the condition

        if self.active == False:

            #Print the string

            print("\nPlease come again.")

            #Return boolean value

            return True

        #Otherwise

        else:

            #Return boolean value

            return False

File name: “atm.py”

#Import packages

from atmmanager import ATMAp, User

from textatm import TextInterface

#Define the function

def main():

    #Assign the value return from TextInterface()

    interface = TextInterface()

    #Assign the value return from ATMApp class

    app = ATMAp("new_atmusers.json", interface)

#Call the function

main()

Sample Output

Content of “new_atmusers.json”:

{

    "users": {

        "xxxx": {

            "userid": "xxxx",

            "pin": "1111",

            "checkin": 2000.0,

            "saving": 11000.0,

            "name": "Christina"

        },

        "ricanontherun": {

            "userid": "ricanontherun",

            "pin": "2112",

            "checkin": 8755.0,

            "saving": 7030.0,

            "name": "Christian"

        },

        "theintimidator": {

            "userid": "theintimidator",

            "pin": "3113",

            "checkin": 1845.0,

            "saving": 112.0,

            "name": "Sean"

        },

        "jazzplusjazzequalsjazz": {

            "userid": "jazzplusjazzequalsjazz",

            "pin": "4114",

            "checkin": 4489.0,

            "saving": 24000.0,

            "name": "Dan"

        }

    }

}

Output:

Welcome to the ATM

Username >> xxxx

Pin >> 1111

Please select a transaction from the approved list. "Check Balance",

 "Withdraw/Deposit Cash", "Transfer Money", "Send Money", "Exit", "Quick Cash $100 >> Check Balance

Checking: 2000.0    Savings: 11000.0

Please select a transaction from the approved list. "Check Balance",

 "Withdraw/Deposit Cash", "Transfer Money", "Send Money", "Exit", "Quick Cash $100 >> Exit

Please come again.

>>>

Additional output:

Welcome to the ATM

Username >> xxxx

Pin >> 1111

Please select a transaction from the approved list. "Check Balance",

 "Withdraw/Deposit Cash", "Transfer Money", "Send Money", "Exit", "Quick Cash $100 >> Withdraw/Deposit Cash

This function will withdraw or deposit cash.

Enter the amount to deposit/withdraw? Enter negative value to withdraw. >> 100

Checking or Savings account? >> Checking

Transaction is complete.

Please select a transaction from the approved list. "Check Balance",

 "Withdraw/Deposit Cash", "Transfer Money", "Send Money", "Exit", "Quick Cash $100 >> Exit

Please come again.

>>>