Objects

COMP122 Lectures 2021-03-02

An object represents a specific, identifiable part of the world-model:

• It incorporates (passive) attributes.
  • Variables.
• It has (active) behaviours, services.
  • Methods.
• Objects interact by sending messages.
  • Calling methods.

Here is an example of three objects:

Here is an interaction between Russ, the ATM near the guild and his account:

graph LR
Russ -->|"requestBalance()"| ATM
ATM -->|152.50| Russ
ATM -->|"getBalance()"| BA[Bank Account]
BA -->|152.50| ATM

Russ has no idea about what happens inside the ATM and only able to directly interact with his account.