epicours/Prog/OOP.md

Object Oriented Programming

Introduction

• A programming paradigm
• Allows:
  • Model objects
  • Make objects interact with each other
• Objcts refer to complex variables

Benefits and motivation

• Modularity
• Abstraction
• Productivity and reusability
• Security and encapsulation

Concrete example

• When we develop a game with cars inside
• We develop the car one time and all other games can re-use the base of the car that we created
• We have access to characteristics
  • Model
  • Color
  • Fuel type
  • ...
• We also have the behavior of the car
  • Start
  • Accelerate
  • Stop

Object

• Data part: object characteristcs
  • Attributes
  • Properties
  • Fields
  • ...
• Code part = oject behavior
  • Methods
  • Procedure

Class

• Object = classs instance
• Class
  • New data type
  • Collection of objects
• Figuratively
  • Class = mold
  • Object = cake
• Class at compilation VS object at runtime

public class MyFirstClass {
  public MyFirstClass() {} //constructor
}
MyFirstClass c = new MyFirstClass(); //new object

Modelization

• First mandatory step

• Data modeling

• UML: Unified Modeling Language

  • Class diagram

  • Class Diagram example:

  • Code example:

    public class MuFirstCar {
      private string _color;
      public string GetColor(){
        return _color;
      }
      public void SetColor(string color){
        _color = color;
      }
    }