Object Orientated Programming

Object Orientated Programming (OOP)- Key Features

Regarding the object-oriented approach to programming there is a relationship between an object, class and method 

• OOP uses objects and classes- and includes both data and associated processing

• Uses classes and methods.

  • • Class: template specifying methods/properties etc. A class defines the methods properties (data) for a group of similar objects

    • Method: program (routine) defined within the class/contained within the object 

• Uses features such as

  • –Encapsulation – technical implementation is hidden within the object.  It involves the protection of attributes and methods of an object so that they can't be accessed or altered by other objects.

  • –Inheritance – is the means by which properties and methods from a class are copied to another class e.g. Mammal to human

  • –Polymorphism – a form of overloading which allows us to create general object structures which can be used with a wider range of data types.  Polymorphism is known as "many forms".

• Once an object is created, knowledge of its implementation is not necessary for its use.  The process of creating an object from a class template is known as INSTANTIATION.

• Objects created using object oriented languages can easily be reused in other programs

• Objects control how other objects interacts with themselves, preventing other kinds of errors, e.g. a programmer cannot set the width of a window to -500

• In some languages, the programmer places objects on forms. These are event-driven languages 

• Enables production of buttons / icons etc. - useful in a visual environment 

• An event, e.g. click a command button, initiates a sequence of code to be executed