TomLafferty / PyPart10

Part 10

Accompanying resources

• Slide deck: https://zipcoder.github.io/reveal-slides.data-engineering/zcw_content/python/fundamentals-part10.html

Exercise 1

Create a program called small_town_teller.py

Declare a Person class with the following attributes:

• id
• first name
• last name

Declare an Account class with the following attributes:

• number
• type
• owner
• balance

Declare a Bank class able to support the following operations:

• Adding a customer to the bank
• Adding an account to the bank
• Removing an account from the bank
• Depositing money into an account
• Withdrawing money from an account
• Balance inquiry for a particular account

From an interactive terminal, you should be able to import these classes an interact with the objects and methods defined above.

Constraints

• When attempting to register a customer, the customer id must be unique.
• When attempting to add an account, the user associated with said account must already registered as a customer.
• When attempting to add an account, the account number must be unique.

from small_town_teller import Person, Account, Bank

zc_bank = Bank()
bob = Person(1, "Bob", "Smith")
zc_bank.add_customer(bob)
bob_savings = Account(1001, "SAVINGS", bob)
zc_bank.add_account(bob_savings)
zc_bank.balance_inquiry(1001)
# 0
zc_bank.deposit(1001, 256.02)
zc_bank.balance_inquiry(1001)
# 256.02
zc_bank.withdrawal(1001, 128)
zc_bank.balance_inquiry(1001)
# 128.02

Exercise 2

Create a program called persistent_small_town_teller.py

Declare a PersistenceUtils class with the following static methods:

• write_pickle
• load_pickle

Append the following methods to the Bank class:

• save_data
• load_data

This application should extend exercise one so that all of the customers and accounts persist between restarts.

From an interactive terminal:

• Create customers and accounts.
• Save the data using the save_data method.
• Exit the session.
• Create a new session.
• Validate there are no customers and no accounts.
• Load the saved data using the load_data method.
• Validate the persistence is working.

from persistent_small_town_teller import Person, Account, Bank

zc_bank = Bank()
zc_bank.customers
# {}
zc_bank.accounts
# {}
zc_bank.load_data()
zc_bank.customers
# {1: <persistent_small_town_teller.Person object at 0x1098e6a90>}
zc_bank.accounts
# {1001: <persistent_small_town_teller.Account object at 0x1099e04d0>}