Advantages and Disadvantages of OOP

Advantages

• Re-usability: re-use the same source-code instead of re-writing it time and time again
• Easier Troubleshooting: able to locate the parts of your code that are not working correctly quickly
• Productivity: a larger number of libraries are readily available
• Problem Solving: more complex problems can be broken down into manageable chunks

Disadvantages

• Learning and Adapting: it does not come naturally to think as an object
• Application Size: more lines of code results in a larger code base
• Applicability: object-oriented programming is not suitable for all applications

Components of OOP

• Important components of object-oriented programming are: classes and objects

Class

• A group of objects that have common properties
• Considered to be a template or blueprint from which an object is created
• Classes are a non-primitive data type, meaning that they are user-defined
• The members of a class are access modifiers, objects, methods, instance variables and constructors

Objects

• An object is an instance of a class
• Any entity that has a property and behaviour are known to be an object

Messages in OOP

• Messages are a request for an object to perform one of its operations
  • simply, the object is calling a function/method of its class
• Messages will be used to define an interface to the object
  • i.e. everything an object can do will be represented by the message interface
• The interface will often be used to provide abstractions
  • i.e. you should not know anything about the implementation in order to use it
• An interface is a set of operations (methods/functions) that a given object can use
  • i.e. setColor(), getColor() etc.

Principles of OOP (2)

Inheritance

• A mechanism where one object will acquire the properties and behaviours of a parent object
  • otherwise, known as a parent-child relationship
• A class can extend another class, hereby inheriting all of its data members and methods
  • known as children
  • the child class can redefine some parents class’ members and methods and/or add its own
• A class can implement an interface, implementing all the specified methods

Principles of OOP (3)

Polymorphism

• Polymorphism is the ability to take more than one form
  • i.e. a class can be used through its parent class interface, but the subclass may override the implementation of an operation it has inherited
• This will allow abstract operations to be defined and used
  • abstract operations will be defined in the parent class’s interface and implemented in the child class

Principles of OOP (4)

Abstraction

• Abstraction means ignoring the irrelevant features, properties or functions and providing emphasis on the relevant ones
  • providing features that are only relevant to the given project
• Abstraction is a process of managing complexity
• We abstract daily in the real-world, by looking at an object, we only see those things that have meaning to us
  • we then abstract the properties of the object and keep only what we need
• It allows us to represent the complex reality in a simplified model
• Abstraction can be used to highlight the properties of an entity that we are most interested in and hide the others

Principles of OOP (5)

Encapsulation

• Encapsulation is where all the data members (or variables) of a class will be declared private
  • this could also include some methods/functions
• Classes interact with other classes only through the class constructors and public methods
• Constructors and public methods of a class serve as an interface to the class