🕵️ PHP Anonymous Classes – Create Lightweight, One-Off Objects on the Fly

Learn how to use anonymous classes in PHP to define and instantiate objects without giving them a formal class name.

🧲 Introduction – What Are Anonymous Classes in PHP?

Anonymous classes in PHP allow you to create a class and an object at the same time, without giving the class a name. Introduced in PHP 7, they’re ideal for short-lived, one-off objects used in event handlers, testing, closures, or temporary logic.

🎯 In this guide, you’ll learn:

• How to create and use anonymous classes
• When to use anonymous classes instead of named ones
• How to implement interfaces or extend classes anonymously
• Best practices for efficient, readable usage

🧱 1. Creating a Basic Anonymous Class

$logger = new class {
    public function log($msg) {
        echo "[LOG]: $msg";
    }
};

$logger->log("Hello world!"); // [LOG]: Hello world!

➡️ Use the new class keyword to define and instantiate simultaneously.
➡️ Perfect for small, self-contained behaviors.

📎 2. Anonymous Class with Constructor

$alert = new class("System failure") {
    private $message;

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

    public function show() {
        echo $this->message;
    }
};

$alert->show(); // System failure

➡️ You can pass constructor arguments just like with regular classes.
➡️ Useful for dependency injection or dynamic configuration.

🧬 3. Implementing Interfaces with Anonymous Classes

interface Greeter {
    public function greet();
}

$greeter = new class implements Greeter {
    public function greet() {
        echo "Hello from anonymous class!";
    }
};

$greeter->greet(); // Hello from anonymous class!

➡️ Anonymous classes can implement interfaces or even extend base classes.
➡️ This is powerful for mocking, strategy patterns, or callbacks.

🧠 4. Extending a Class Anonymously

class BaseLogger {
    public function info($msg) {
        echo "[INFO]: $msg";
    }
}

$customLogger = new class extends BaseLogger {
    public function error($msg) {
        echo "[ERROR]: $msg";
    }
};

$customLogger->info("Start");
$customLogger->error("Something went wrong");

➡️ You can extend existing classes to enhance or override functionality.
➡️ Makes temporary modifications easy without creating a new class file.

🧠 Best Practices

• ✅ Use for quick, local objects that don’t need reuse
• ✅ Keep logic simple and self-contained
• ✅ Implement interfaces when using in dependency injection
• ❌ Don’t use for large logic blocks — prefer named classes
• ✅ Useful in testing, mocks, and closures

📌 Summary – Recap & Next Steps

PHP anonymous classes provide a lightweight alternative to regular class definitions when you only need the behavior once. They offer the full power of classes — constructors, inheritance, interfaces — all inline.

🔍 Key Takeaways:

• Anonymous classes are created using new class {}
• Great for short-lived, one-off objects
• Support inheritance, interfaces, constructors, and visibility
• Cleaner than defining throwaway named classes

⚙️ Real-World Use Cases:
Temporary formatters, test mocks, closure callbacks, inline service implementations, strategy pattern injections

❓ Frequently Asked Questions (FAQs)

❓ When should I use an anonymous class?
✅ When you need a one-time-use class and want to avoid cluttering your codebase.

❓ Can anonymous classes have properties and methods?
✅ Yes, just like regular classes — including private, public, protected.

❓ Can anonymous classes be reused?
❌ No. Once instantiated, they’re not referenceable by name.

❓ Can I type-hint an anonymous class?
✅ Only if it implements an interface or extends a known base class.

❓ Are anonymous classes slower than named classes?
🔸 Slightly — but the performance impact is negligible in most applications.