Hands-On Design Patterns and Best Practices with Julia

Composing a new type that contains an existing type

As part of a new initiative, the bank wants us to support a new savings account product, which provides daily interest for customers. Since the existing account management's functionality is critical to the bank's business and is maintained by a different team, we have decided to reuse its functionality without touching any of the existing source code.

First, let's create our own SavingsAccount data type, as follows:

struct SavingsAccount    acct::Account    interest_rate::Float64        SavingsAccount(account_number, balance, date_opened, interest_rate) = new(        Account(account_number, balance, date_opened),        interest_rate    )end

The first field, acct, is used to hold an Account object, while the second ...