# PHP Reflection API

PHP comes with a complete reflection API that adds the ability to reverse-engineer classes, interfaces, functions, methods and extensions. Additionally, the reflection API offers ways to retrieve doc comments for functions, classes and methods.

---

## 1. ReflectionClass
The `ReflectionClass` class reports information about a class.

```php
class User {
    public $username;
    private $password;

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

    public function getUsername() {
        return $this->username;
    }
}

$reflector = new ReflectionClass('User');

echo $reflector->getName(); // Outputs: User
print_r($reflector->getProperties()); // Outputs array of ReflectionProperty objects
print_r($reflector->getMethods()); // Outputs array of ReflectionMethod objects
```

## 2. ReflectionMethod
The `ReflectionMethod` class reports information about a method.

```php
$method = new ReflectionMethod('User', 'getUsername');

if ($method->isPublic()) {
    echo "The method is public.";
}
```

## 3. Invoking Private Methods
Reflection can be used to bypass visibility modifiers (useful for testing).

```php
$user = new User('JohnDoe');
$reflector = new ReflectionClass('User');
$property = $reflector->getProperty('password');
$property->setAccessible(true);
$property->setValue($user, 'secret123');

print_r($user);
```

## 4. Use Cases
*   **Dependency Injection Containers:** Automatically instantiating classes and resolving their dependencies by inspecting constructor type hints.
*   **Automated Testing:** Testing private methods or properties.
*   **Documentation Generators:** Reading DocBlocks to generate API documentation.

[[programming/php/php]] [[programming/php/php-classes]]