Object Orientation and Aion DS

1
Object Orientation and Aion DS

• An object within Aion DS is called a CLASS
• Associated functions that work with the class are
  called METHODS
• Classes describe the object but contain no data

2
Object Orientation and Aion DS

• An object within Aion DS is called a CLASS
• Associated functions that work with the class are
  called METHODS
• Classes describe the object but contain no data

Class - Bank Account
Owner Balance
Data I.e. Slots
Print balance Deposit money
Methods
3
Object Orientation and Aion DS

• To use an object, we must create an INSTANCE of
  the class, which is a specific occurrence of that
  class

Class - Bank Account
Instance 1 - Bank Account
Instance 2 - Bank Account
Owner Balance
Owner - Mr. Smith Balance - 150
Owner - Ms. Jones Balance - 2,300
Print balance Deposit money
4
Object Orientation and Aion DS

• Classes can be defined in hierarchies
• This allows -
• The re-use of data definitions and procedures
• The customisation or specialisation of code
• The modeling of components within the application
  domain

5
Object Orientation and Aion DS

• Inheritance with Specialisation

Class - Bank Account
Owner Balance
Print balance Deposit money
Class - Current Account
Class - Deposit Account
Overdraft Limit Current Overdraft
Interest Rate
Calculate Interest
Arrange Overdraft
6
Object Orientation and Aion DS

• Advantages of OO programming compared with
  traditional programming approaches
• Information represented in the classes and
  instances is self contained and easily
  transportable
• Having procedures or methods centrally located in
  classes helps eliminate redundancy in the
  representation of procedural logic
• Breaking down complex procedures into smaller
  pieces of re-usable code makes procedural logic
  more modular
• Using class hierarchies facilitates code re-use
  and enables easy customisation or specialisation
  of behaviour

7
Object Orientation and Aion DS

• Aion DS supports OO programming
• For very simple KBSs, where multiple classes,
  inheritance, specialisation and procedural
  methods, are not required, classes are still used
  as the method for storing data.
• Slots may be required to store inferences made by
  the system.
• For example in a medical diagnosis expert system
  a class Person may have slots Illness and
  Drugs to be taken both of which will be
  inferred by the system as it makes its diagnosis
  and decides upon the appropriate medicines to be
  taken.