What are the best practices for handling dependencies between classes in PHP?

When handling dependencies between classes in PHP, it is best practice to use dependency injection to inject dependencies into a class rather than creating them within the class itself. This promotes loose coupling between classes, making them easier to test and maintain. Additionally, using interfaces can help define contracts for dependencies, allowing for easier substitution of implementations. 

// Dependency Injection Example
class Dependency {
    public function doSomething() {
        return 'Doing something';
    }
}

class MyClass {
    private $dependency;

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

    public function useDependency() {
        return $this->dependency->doSomething();
    }
}

$dependency = new Dependency();
$myClass = new MyClass($dependency);
echo $myClass->useDependency(); // Output: Doing something

Keywords

autoloading composer namespaces dependency injection class coupling

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