7 Important basic topics about Software Development

1. Abstract Class:

An abstract class in object-oriented programming is a blueprint for creating objects that defines some behavior (methods) but leaves some implementation details incomplete. It cannot be directly instantiated (created as an object). Here’s the purpose:

Enforces common behavior: Abstract classes define methods that subclasses must implement, ensuring consistency across related objects.
Partial implementation: You can provide default implementations for some methods in an abstract class, reducing redundancy in subclasses.
Code organization: Abstract classes help structure code by grouping related functionalities.

2. Interfaces:

Interfaces are contracts that define what methods a class must implement. They specify the behavior a class must exhibit but don’t provide any implementation. Here’s why they’re useful:

Decoupling: Interfaces promote loose coupling between classes, making code more flexible and maintainable.
Standardized behavior: Interfaces ensure that any class implementing them provides the required functionality.
Multiple inheritance: In some languages (like Java), interfaces allow a class to inherit behavior from multiple sources without the complexities of traditional multiple class inheritance.

3. Properties in Interfaces:

In most languages (like PHP and C#), interfaces cannot directly declare properties. However, some languages (like TypeScript) allow interfaces to define property signatures, specifying the property name, type, and whether it’s optional or readonly.

4. Interface Implementation in Parent Class:

If a parent class implements an interface, its child classes do not necessarily have to implement the same interface. Here’s the inheritance relationship:

InterfaceA
  |
 ParentClass (implements InterfaceA)
  |
 ChildClass1 (might or might not implement InterfaceA)
  |
 ChildClass2 (might or might not implement InterfaceA)

Child classes inherit the implemented methods from the parent class but are not forced to implement the interface themselves, unless they need to directly use the interface’s functionality.

5. Basic Layers of a Backend Framework:

Here’s a breakdown of common layers in a backend frameworks:

HTTP Layer: Handles incoming HTTP requests, parses data (headers, body, query string), and routes the request to the appropriate handler.
Routing Layer: Analyzes the request URL and maps it to a specific controller or function in your application.
Controller Layer: Contains business logic, interacts with models and views, and determines the application’s response.
Model Layer: Represents the data structures and logic associated with your data (often interacting with a database).
View Layer: Responsible for presenting the data to the user, typically using templates or generating HTML.

6. Polymorphism:

Polymorphism is a concept in object-oriented programming that allows objects of different types to respond to the same method call in different ways. It’s achieved through two main mechanisms:

Method Overriding: In inheritance, a subclass can redefine a method inherited from its parent class, providing its own specific implementation. When you call the method on a subclass object, the overridden version is executed.
Interfaces: As mentioned earlier, interfaces define behavior. When a method is called on a variable that refers to an object through an interface, the appropriate implementation based on the object’s actual type is executed at runtime (dynamic binding). This allows you to write generic code that works with objects of different types as long as they implement a common interface.

Polymorphism makes code more flexible, reusable, and easier to maintain.

7. Polymorphism:

Example of Polymorphism in PHP:

<?php

// Define an abstract class Animal
abstract class Animal {
  public abstract function makeSound(): string;
}

// Define child classes for Dog and Cat
class Dog extends Animal {
  public function makeSound(): string {
    return "Woof!";
  }
}

class Cat extends Animal {
  public function makeSound(): string {
    return "Meow!";
  }
}

// Function to make animals speak (polymorphic)
function makeAnimalSpeak(Animal $animal) {
  return $animal->makeSound();
}

// Create instances of Dog and Cat
$dog = new Dog();
$cat = new Cat();

// Call makeAnimalSpeak with both Dog and Cat objects
echo $makeAnimalSpeak($dog) . PHP_EOL; // Output: Woof!
echo $makeAnimalSpeak($cat) . PHP_EOL; // Output: Meow!

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