4.2.9. Initialization

Any object requiring initialization at creation time must define an INIT method. If this method is defined, the class object runs the INIT method after the object is created. If an object has more than one INIT method (for example, it is defined in several classes), each INIT method must forward the INIT message up the hierarchy to complete the object's initialization.

Example 4.12. Instance initialization

asav = .savings~new(1000.00, 6.25)
say asav~type
asav~name = "John Smith"

::class Account

::method INIT
  expose balance
  use arg balance

::method TYPE
  return "an account"

::method name attribute

::class Savings subclass Account

::method INIT
  expose interest_rate
  use arg balance, interest_rate
  self~init:super(balance)

::method type
  return "a savings account"

The NEW method of the Savings class object creates a new Savings object and calls the INIT method of the new object. The INIT method arguments are the arguments specified on the NEW method. In the Savings INIT method, the line:

Example 4.13. Instance initialization

self~init:super(balance)

calls the INIT method of the Account class, using just the balance argument specified on the NEW message.