PHP Inheritance and Method Overrides

The feature illustrated below operates on PHP values, objects, or language metadata.

What Is Inheritance and Method Overrides in PHP?

Interfaces define contracts, inheritance specializes related types, and composition delegates responsibilities to collaborators.

Example 1: Understanding the Basic Behavior

<?php

interface Reporter { public function report(): string; }
class JsonReporter implements Reporter { public function report(): string { return '{"ok":true}'; } }
echo (new JsonReporter())->report();

Output:

{"ok":true}

Explanation: Interfaces define contracts, inheritance specializes related types, and composition delegates responsibilities to collaborators.

Example 2: Testing Another Case

<?php

class Logger { public function write(string $message): void { echo $message; } }
class Worker { public function __construct(private Logger $logger) {} public function run(): void { $this->logger->write('working'); } }
(new Worker(new Logger()))->run();

Output:

working

Explanation: A child class can replace an inherited method implementation while preserving the parent method contract.

Practical Example: Applying the Operation

<?php

abstract class Payment { abstract public function label(): string; }
class CardPayment extends Payment { public function label(): string { return 'Card'; } }
echo (new CardPayment())->label();

Output:

Card

Explanation: Use parent::method() only when the parent behavior should be included; violating compatible parameter and return types is not a valid override.

Important Behavior and Edge Cases

• A child class can replace an inherited method implementation while preserving the parent method contract.
• Use parent::method() only when the parent behavior should be included; violating compatible parameter and return types is not a valid override.

Comparison With Related Approaches

Common Beginner Mistakes

Key Takeaways

• Interfaces define contracts, inheritance specializes related types, and composition delegates responsibilities to collaborators.
• A child class can replace an inherited method implementation while preserving the parent method contract.
• Use parent::method() only when the parent behavior should be included; violating compatible parameter and return types is not a valid override.

The examples demonstrate where Inheritance and Method Overrides fits within php programming. Verify the relevant preconditions whenever you adapt the code to real data.