PHP OOP Abstract Classes

PHP OOP – Abstract Classes

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An abstract class is a class that cannot be instantiated (you cannot create objects from it).
It is used as a base/blueprint for other classes.

🔥 Key Points About Abstract Classes

✔ You cannot create an object of an abstract class
✔ Abstract class may have abstract methods (no body)
✔ Child class must override abstract methods
✔ Can have normal methods also
✔ Supports properties & constructors
✔ Supports protected & private members
✔ Supports inheritance

🟦 1️⃣ Basic Abstract Class Example

You cannot do:

🟩 2️⃣ Child Class Must Define Abstract Method

🟧 3️⃣ Abstract Class with Normal Method

abstract class Vehicle {

public function start() {
echo "Starting engine...<br>";
}

abstract public function wheels();
}

class Car extends Vehicle {
public function wheels() {
echo "Car has 4 wheels";
}
}

$c = new Car();
$c->start();
$c->wheels();

abstract class Vehicle {

public function start() {

echo "Starting engine...<br>";

}

abstract public function wheels();

}

class Car extends Vehicle {

public function wheels() {

echo "Car has 4 wheels";

}

$c = new Car();

$c->start();

$c->wheels();

🟥 4️⃣ Abstract Class with Constructor

abstract class Person {
public $name;

public function __construct($name) {
$this->name = $name;
}

abstract public function role();
}

class Student extends Person {
public function role() {
return "Student: " . $this->name;
}
}

$st = new Student("Rahul");
echo $st->role();

abstract class Person {

public $name;

public function __construct($name) {

$this->name = $name;

}

abstract public function role();

}

class Student extends Person {

public function role() {

return "Student: " . $this->name;

}

$st = new Student("Rahul");

echo $st->role();

abstract class Person {
public $name;

public function __construct($name) {
$this->name = $name;
}

abstract public function role();
}

class Student extends Person {
public function role() {
return "Student: " . $this->name;
}
}

$st = new Student("Rahul");
echo $st->role();

abstract class Person {

public $name;

public function __construct($name) {

$this->name = $name;

}

abstract public function role();

}

class Student extends Person {

public function role() {

return "Student: " . $this->name;

}

$st = new Student("Rahul");

echo $st->role();

🟫 5️⃣ Multiple Abstract Methods

abstract class Shape {
abstract public function area();
abstract public function perimeter();
}

class Rectangle extends Shape {
public function area() {
return 10 * 5;
}

public function perimeter() {
return 2 * (10 + 5);
}
}

abstract class Shape {

abstract public function area();

abstract public function perimeter();

}

class Rectangle extends Shape {

public function area() {

return 10 * 5;

}

public function perimeter() {

return 2 * (10 + 5);

}

🟪 6️⃣ Why Use Abstract Classes?

✔ Forces child classes to follow rules
✔ Ensures structure/pattern
✔ Useful when many classes share common behavior
✔ Helpful in large applications
✔ Used widely in frameworks like Laravel

Example: Laravel controller

All controllers extend it.

🟧 7️⃣ Abstract Class vs Interface (Important)

Feature	Abstract Class	Interface
Methods	Both normal + abstract	Only abstract (PHP 7), can have default in PHP 8
Constructor	✔ Yes	❌ No
Properties	✔ Yes	✔ (public only)
Multiple inheritance	❌ No	✔ Implement multiple interfaces
Use case	When base class is needed	When only rules are needed

🟩 Practical Example

Making a universal payment system:

abstract class Payment {
abstract public function pay($amount);
}

class Paytm extends Payment {
public function pay($amount) {
echo "Paid $amount via Paytm";
}
}

class Paypal extends Payment {
public function pay($amount) {
echo "Paid $amount via PayPal";
}
}

$p = new Paytm();
$p->pay(100);

abstract class Payment {

abstract public function pay($amount);

}

class Paytm extends Payment {

public function pay($amount) {

echo "Paid $amount via Paytm";

}

class Paypal extends Payment {

public function pay($amount) {

echo "Paid $amount via PayPal";

}

$p = new Paytm();

$p->pay(100);

🎯 Summary (Easy to Remember)

Concept	Meaning
abstract class	Cannot make object, used as base
abstract method	Must be implemented by child
extends	Child inherits abstract class
Purpose	Enforce structure in child classes

PHP OOP Abstract Classes

PHP OOP – Abstract Classes

🔥 Key Points About Abstract Classes

🟦 1️⃣ Basic Abstract Class Example

🟩 2️⃣ Child Class Must Define Abstract Method

🟧 3️⃣ Abstract Class with Normal Method

🟥 4️⃣ Abstract Class with Constructor

🟫 5️⃣ Multiple Abstract Methods

🟪 6️⃣ Why Use Abstract Classes?

Example: Laravel controller

🟧 7️⃣ Abstract Class vs Interface (Important)

🟩 Practical Example

Making a universal payment system:

🎯 Summary (Easy to Remember)

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PHP OOP Abstract Classes

PHP OOP – Abstract Classes

🔥 Key Points About Abstract Classes

🟦 1️⃣ Basic Abstract Class Example

🟩 2️⃣ Child Class Must Define Abstract Method

🟧 3️⃣ Abstract Class with Normal Method

🟥 4️⃣ Abstract Class with Constructor

🟫 5️⃣ Multiple Abstract Methods

🟪 6️⃣ Why Use Abstract Classes?

Example: Laravel controller

🟧 7️⃣ Abstract Class vs Interface (Important)

🟩 Practical Example

Making a universal payment system:

🎯 Summary (Easy to Remember)

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