OOP BASICS

Encapsulation

The property's and functions of the functionality/component are all put together inside a object.

Abstraction

As opposed to encapsulation, abstraction tends to generalize things, hiding unwanted data and revealing necessary data.

Polymorphism

Polymorphism, in short, is the ability for data to be represented in more than one way.

Inheritance

Elements inherit the properties and methods of the father class.

Access Identifiers

Public: access this property everywhere. Public methods can access private properties
Private: only accessibly inside the class.
Protected: access inside the original and the children of that class.

Constructor

Function that runs when a new instance of the class is declared.

public function __construct() {
    echo 'Object declared';
}

Destructor

Function that runs when the call to an object finishes.

public function __destructor() {
    echo 'Object last run';
}

Extend a class

A new class inherits the properties of the extended class.

class Human extends Animal {
    // all the animal public and protected 
    // properties and methods are inherit
}

Scope Resolution Operator

"Get the parent of this object then call its constructor".

class Son extends Father
{
    function __construct($name, $email)
    {
        parent::__construct($name);
        $this->email = $email;
    }
}

Abstract classes & methods

Class that can only be inherit. The abstract methods can have a body. Only declare the name, properties & result.

abstract class Think 
{
    public abstract function remember ($try) : string;
}

Static

Properties and methods of a class can be static with the purpose of call them without the need of declare the class.

class User {
    private static $password = 1234;

    public statis function getPassword () {
        return self::$password;
    }
}
echo User::$password; // returns 1234;

Type declarations of members.

Used to declare what kind of values a variable must contain.

public string $animal = 'Dog';

Theory

1. What is object-oriented programming in general terms?

Programming paradigm that uses abstraction to encapsulate all the
concepts and functionalities of a abstract element. Its used to have a
better organization of the code, better escalability and repeat less code.

2. What is a class?

Blueprint that contains all the properties and functionalities of a main 
concept. So from that class we can create various elements with the same 
caracteristics. The classes can inherit other classes public and protected 
properties and methods.

3. What is an object?

A list of properties and functions.

4. What is an instance?

The declaration of a object.

5. What is a property?

Variable inside a object that contains data value.

6. What is a method?

Function inside a object.

7. What is the difference between a function and a method?

A method its a called always from the object that contains it.

8. What is a constructor?

Magic method from a class that runs automatically when a object is created.
It is normally used to add properties on the object declaration.

9. What is the difference between a class, an object and an instance?

Class is the template of a future object/s. An instance indicates the 
relation between object and class. So a object its a instance of a class.

14. What do we understand by the concept of Overload?

Using the __call magic method to change the function body and behavior 
depending on the number and type of arguments given.

class Thing {
    function __call ($nameFunction, $arguments) {

        switch(count($arguments)) {
            case 1:
                return 'Only one argument';
            case 2:
                return 'Two arguments';
        }
    }
}

$thing = new Thing;
echo $thing->argumentCounter('a'); // Only one argument
echo $thing->argumentCounter('a','b'); // Two arguments

15. What do we understand by the concept of Override?

Replace a parent method in a child class.

16. What differences exist between the concept of Overload and Override?

Overload its a magic method to create diferent outputs for the same method.
Override only refears to changing the logic of a method inherit form the 
parent class.

17. What is a static class?

RESPONSE

18. Look for 3 advantages over object-oriented programming compared to other programming paradigms

1. DRY code.
2. Better scalability.
3. Organized code.

19. Look for disadvantages of this paradigm.

1. More complex.
2. Needs planing.

marcelarie / oop-basics