Belajar PHP Dasar | 15. Belajar OOP PHP Dasar (Inheritance)

Summary

In this tutorial, the speaker explains the concept of inheritance in PHP's Object-Oriented Programming (OOP). Using relatable analogies, such as parent-child relationships, they demonstrate how a subclass can inherit properties and methods from a parent class. The tutorial covers key topics like constructor inheritance, method inheritance, and how PHP’s `extends` keyword facilitates this. Practical PHP code examples show how inheritance works in real-world coding scenarios, like connecting a database. By the end, viewers gain a solid understanding of how inheritance enhances code reusability and structure in OOP.

Takeaways

• 😀 Inheritance in OOP allows a child class to inherit properties and methods from a parent class, simplifying code reuse and reducing redundancy.
• 😀 Inheritance is a concept common to multiple programming languages, including PHP, Java, and C++, not just PHP.
• 😀 Analogies, like children inheriting physical traits from parents, are used to explain how inheritance works in programming.
• 😀 A child class can access methods and properties of its parent class without having to redefine them.
• 😀 The keyword 'extends' is used to define a child class that inherits from a parent class.
• 😀 Inheritance helps with memory optimization by avoiding duplicate code.
• 😀 A constructor from the parent class can be inherited by the child class, meaning the child class doesn't need to define its own constructor unless customization is needed.
• 😀 The child class can use methods from the parent class even if those methods are not explicitly defined in the child class.
• 😀 Using inheritance in real-world applications, like database management, allows for efficient and modular code structures where child classes can perform specific tasks based on the parent class.
• 😀 The tutorial demonstrated inheritance using both a fruit analogy (Fruit and Strawberry) and a human analogy (Parent and Child) to make the concept more relatable.
• 😀 Inheritance in PHP, and OOP in general, is a powerful concept that can simplify large codebases, especially when dealing with complex objects or systems.

Q & A

What is inheritance in OOP?

Inheritance is a concept in Object-Oriented Programming (OOP) where a class (child class) derives properties and methods from another class (parent class). It allows code reuse and the creation of more specialized classes.

How is inheritance implemented in PHP?

In PHP, inheritance is implemented using the `extends` keyword. A child class can inherit methods and properties from a parent class, allowing the child class to reuse code defined in the parent class.

What analogy is used to explain inheritance in the script?

The script uses the analogy of parents passing on their properties to their children. For example, if a father has blonde hair, the child is likely to have blonde hair as well, just like a child class inheriting properties and methods from a parent class.

Why is inheritance useful in programming?

Inheritance is useful because it helps reduce redundancy by allowing child classes to reuse code from parent classes. This improves maintainability and memory efficiency, as common functionality does not need to be rewritten.

What happens when a child class inherits from a parent class without explicitly defining a method?

If a child class does not define a method but inherits from a parent class, it can still use the methods defined in the parent class. This is because the child class automatically inherits all public methods from the parent class.

What role does the `parent` keyword play in PHP inheritance?

The `parent` keyword in PHP is used to access methods and properties from the parent class. It allows the child class to call parent methods, including the constructor, without needing to redefine them.

How does the constructor function work in inheritance?

When a child class inherits from a parent class, the child class can call the parent class's constructor using `parent::__construct()`. This ensures that the parent class's initialization code runs before the child class's code.

Can a child class override methods from a parent class?

Yes, a child class can override methods from a parent class by redefining them. However, the child class must ensure that the method signature matches the parent class method, or it may result in an error.

In the example, what is the significance of the `extends` keyword in the child class?

In the example, the `extends` keyword indicates that the child class (e.g., `anak`) is inheriting from the parent class (e.g., `orang tua`). This allows the child class to access the parent class’s methods and properties.

What would happen if the `parent::__construct()` call were omitted in the child class?

If `parent::__construct()` is omitted in the child class, the parent class's constructor will not be executed, potentially leaving uninitialized properties or causing errors if the parent class constructor is required.