? PHP OOP Interfaces

? Quick Overview

An interface in PHP defines a strict contract that classes must follow. It specifies method signatures without implementations and ensures consistency across different class implementations.

? Key Concepts

• Interfaces contain only method declarations
• No properties or method bodies are allowed
• Classes must implement all interface methods
• Supports multiple inheritance of behavior
• Useful for dependency injection and type hinting

? Syntax & Theory

Interfaces are declared using the interface keyword. A class uses the implements keyword to follow the interface contract.

// Defining an interface with a required method
<?php
interface Logger {
public function log($message);
}

class FileLogger implements Logger {
public function log($message) {
echo "Logging to file: ".$message;
}
}

$logger = new FileLogger();
$logger->log("Test message");
?>

? Interactive Concept Flow

Interface ➜ Implements ➜ Class ➜ Method Execution

?️ Use Cases

• Standardizing APIs across multiple classes
• Implementing dependency injection
• Ensuring interchangeable class behavior
• Designing loosely coupled systems
• Creating testable and maintainable code