Bank Ledger

Part of the Object Oriented Programming section of Coddy's Ruby journey. Lesson 57 of 57.

Challenge

Hard

Build a small bank. BankError < StandardError is the parent of InvalidAmount, InsufficientFunds, LimitReached and NoAccount, which carry the messages invalid amount, insufficient funds in 2, withdrawal limit on 2 and no account 9. Account.new(id, owner) has readers for id, owner and balance, with a private setter for the balance. deposit(amount) and withdraw(amount) raise InvalidAmount below 1; withdraw raises InsufficientFunds when the balance would fall below lowest_balance, a hook that returns 0. month_end does nothing and kind returns the account type. Checking allows an overdraft down to -100. Savings allows at most 2 withdrawals per month (LimitReached), and its month_end adds 1% interest, rounded down, and resets the count. to_s returns 1 ada checking: -20. Bank#open(kind, id, owner) creates a Checking or Savings, account(id) raises NoAccount, transfer(from, to, amount) looks both accounts up before it withdraws and deposits, month_end calls it on every account, and Bank includes Enumerable with each yielding the accounts by id.

The supplied code reads commands open checking 1 ada, dep 1 100, wd 2 30, tr 1 2 50 or month, prints ok or the error message for each, and finally every account.

Your code goes in bank_error.rb, invalid_amount.rb, insufficient_funds.rb, limit_reached.rb, no_account.rb, account.rb, checking.rb, savings.rb and bank.rb. main.rb holds the supplied input/output code and cannot be edited.

Try it yourself

require_relative 'bank_error'
require_relative 'invalid_amount'
require_relative 'insufficient_funds'
require_relative 'limit_reached'
require_relative 'no_account'
require_relative 'account'
require_relative 'checking'
require_relative 'savings'
require_relative 'bank'

# Supplied input/output code: keep it as it is
input = []
while (line = gets)
  input << line.chomp
end
bank = Bank.new
input.each do |cmd|
  parts = cmd.split
  begin
    case parts[0]
    when "open" then bank.open(parts[1], parts[2].to_i, parts[3])
    when "dep" then bank.account(parts[1].to_i).deposit(parts[2].to_i)
    when "wd" then bank.account(parts[1].to_i).withdraw(parts[2].to_i)
    when "tr" then bank.transfer(parts[1].to_i, parts[2].to_i, parts[3].to_i)
    else bank.month_end
    end
    puts "ok"
  rescue BankError => e
    puts e.message
  end
end
bank.each { |account| puts account }