Traits

<?php
trait Timestamps {
    public function createdAt(): string {
        return date("Y-m-d H:i:s");
    }

    public function updatedAt(): string {
        return date("Y-m-d H:i:s");
    }
}

trait SoftDeletes {
    private bool $deleted = false;

    public function delete(): void {
        $this->deleted = true;
    }

    public function isDeleted(): bool {
        return $this->deleted;
    }

    public function restore(): void {
        $this->deleted = false;
    }
}

class User {
    use Timestamps, SoftDeletes;  // Use multiple traits!

    public function __construct(public string $name) {}
}

class Post {
    use Timestamps, SoftDeletes;

    public function __construct(public string $title) {}
}

$user = new User("John");
echo $user->createdAt();   // 2025-05-22 10:00:00
$user->delete();
echo $user->isDeleted();   // true

$post = new Post("My Article");
echo $post->createdAt();   // same trait, different class
?>

<?php
trait Validatable {
    abstract protected function rules(): array;

    public function validate(array $data): bool {
        foreach ($this->rules() as $field => $rule) {
            if ($rule === 'required' && empty($data[$field])) {
                echo "Field '$field' is required\n";
                return false;
            }
        }
        return true;
    }
}

class LoginForm {
    use Validatable;

    protected function rules(): array {
        return [
            'email'    => 'required',
            'password' => 'required',
        ];
    }
}

$form = new LoginForm();
$form->validate(['email' => '', 'password' => '123']);
// Field 'email' is required
?>