Patrones de diseño en XOOPS

2.5.x ✅ 4.0.x ✅

Los patrones de diseño son soluciones reutilizables a problemas comunes de diseño de software. XOOPS emplea varios patrones bien establecidos que ayudan a mantener la calidad del código, mejorar la capacidad de prueba y mejorar la flexibilidad del sistema.

Selección rápida de patrones

¿No está seguro de qué patrón usar? Consulte:

• Elegir un patrón de acceso a datos — controladores vs repositorio vs servicio vs CQRS
• Elegir un sistema de eventos — precargas vs eventos PSR-14

Descripción general

Entender e implementar correctamente los patrones de diseño es crucial para crear módulos XOOPS mantenibles. Esta guía cubre los patrones más utilizados en el desarrollo de XOOPS.

Patrón	Propósito	Casos de uso comunes
MVC	Separación de preocupaciones	Estructura del módulo
Singleton	Garantía de instancia única	Conexiones de base de datos
Factory	Abstracción de creación de objetos	Controladores, base de datos
Observer	Notificación de eventos	Precargas, notificaciones
Decorator	Extensión de comportamiento dinámico	Elementos de formulario, filtros
Strategy	Intercambio de algoritmos	Autenticación, validación
Adapter	Compatibilidad de interfaz	Integración de código heredado
Repository	Abstracción de acceso a datos	Persistencia de datos

Model-View-Controller (MVC)

The MVC pattern separates an application into three interconnected components, making the codebase more organized and testable.

Architecture

flowchart TB
    subgraph MVC["MVC Pattern in XOOPS"]
        Controller["🎮 Controller<br/>(index.php, admin/index.php)"]
        Model["📦 Model<br/>(Handlers)"]
        View["🎨 View<br/>(Templates)"]

        Controller --> Model
        Controller --> View
        Model <--> View
    end

    style Controller fill:#e3f2fd,stroke:#1976d2
    style Model fill:#fff3e0,stroke:#f57c00
    style View fill:#e8f5e9,stroke:#388e3c

Model (Data Layer)

<?php
namespace XoopsModules\MyModule;

class Article extends \XoopsObject
{
    public function __construct()
    {
        $this->initVar('article_id', XOBJ_DTYPE_INT, null, false);
        $this->initVar('title', XOBJ_DTYPE_TXTBOX, '', true, 255);
        $this->initVar('content', XOBJ_DTYPE_TXTAREA, '', true);
        $this->initVar('author_id', XOBJ_DTYPE_INT, 0, true);
        $this->initVar('status', XOBJ_DTYPE_INT, 1, false);
        $this->initVar('created', XOBJ_DTYPE_INT, time(), false);
        $this->initVar('modified', XOBJ_DTYPE_INT, time(), false);
    }

    public function isPublished(): bool
    {
        return $this->getVar('status') === 1;
    }

    public function getFormattedDate(): string
    {
        return formatTimestamp($this->getVar('created'));
    }
}

class ArticleHandler extends \XoopsPersistableObjectHandler
{
    public function __construct(\XoopsDatabase $db)
    {
        parent::__construct($db, 'mymodule_articles', Article::class, 'article_id', 'title');
    }

    public function getPublishedArticles(int $limit = 10): array
    {
        $criteria = new \CriteriaCompo();
        $criteria->add(new \Criteria('status', 1));
        $criteria->setSort('created');
        $criteria->setOrder('DESC');
        $criteria->setLimit($limit);

        return $this->getObjects($criteria);
    }
}

View (Presentation Layer)

{* templates/article_list.tpl *}
<div class="article-list">
    <h2>{$smarty.const._MD_MYMODULE_ARTICLES}</h2>

    {foreach from=$articles item=article}
        <article class="article-item">
            <h3>
                <a href="{$xoops_url}/modules/mymodule/article.php?id={$article.article_id}">
                    {$article.title|escape}
                </a>
            </h3>
            <p class="meta">
                {$smarty.const._MD_MYMODULE_POSTED}: {$article.formatted_date}
            </p>
            <div class="content">
                {$article.content|truncate:200}
            </div>
        </article>
    {/foreach}
</div>

Controller (Logic Layer)

index.php

<?php
require_once dirname(__DIR__, 2) . '/mainfile.php';

use XoopsModules\MyModule\Helper;

$helper = Helper::getInstance();
$articleHandler = $helper->getHandler('Article');

// Get action from request
$op = \Xmf\Request::getString('op', 'list');

switch ($op) {
    case 'view':
        $articleId = \Xmf\Request::getInt('id', 0);
        $article = $articleHandler->get($articleId);

        if (!$article) {
            redirect_header(XOOPS_URL, 3, _MD_MYMODULE_NOT_FOUND);
        }

        $GLOBALS['xoopsOption']['template_main'] = 'mymodule_article_view.tpl';
        require_once XOOPS_ROOT_PATH . '/header.php';

        $xoopsTpl->assign('article', $article->toArray());
        break;

    case 'list':
    default:
        $articles = $articleHandler->getPublishedArticles(10);

        $GLOBALS['xoopsOption']['template_main'] = 'mymodule_article_list.tpl';
        require_once XOOPS_ROOT_PATH . '/header.php';

        $xoopsTpl->assign('articles', array_map(fn($a) => $a->toArray(), $articles));
        break;
}

require_once XOOPS_ROOT_PATH . '/footer.php';

Singleton Pattern

The Singleton pattern ensures a class has only one instance and provides global access to it.

When to Use

• Database connections
• Configuration managers
• Logger instances
• Cache managers

Implementation

<?php
namespace XoopsModules\MyModule;

class ConfigurationManager
{
    private static ?self $instance = null;
    private array $config = [];

    private function __construct()
    {
        // Load configuration
        $this->loadConfiguration();
    }

    // Prevent cloning
    private function __clone() {}

    // Prevent unserialization
    public function __wakeup()
    {
        throw new \Exception("Cannot unserialize singleton");
    }

    public static function getInstance(): self
    {
        if (self::$instance === null) {
            self::$instance = new self();
        }

        return self::$instance;
    }

    private function loadConfiguration(): void
    {
        $helper = Helper::getInstance();
        $this->config = [
            'items_per_page' => $helper->getConfig('items_per_page', 10),
            'allow_comments' => $helper->getConfig('allow_comments', true),
            'date_format' => $helper->getConfig('date_format', 'Y-m-d'),
        ];
    }

    public function get(string $key, mixed $default = null): mixed
    {
        return $this->config[$key] ?? $default;
    }
}

// Usage
$config = ConfigurationManager::getInstance();
$itemsPerPage = $config->get('items_per_page');

XOOPS Core Examples

<?php
// XoopsDatabaseFactory uses Singleton pattern
$db = XoopsDatabaseFactory::getDatabaseConnection();

// XMF Module Helper uses Singleton
$helper = \Xmf\Module\Helper::getHelper('mymodule');

// Xoops main instance
$xoops = \Xoops::getInstance();

Factory Pattern

The Factory pattern creates objects without specifying their exact class, allowing for flexible object creation.

When to Use

• Creating handlers dynamically
• Database connections for different databases
• Authentication providers
• Form element creation

Implementation

<?php
namespace XoopsModules\MyModule;

interface ContentInterface
{
    public function render(): string;
}

class ArticleContent implements ContentInterface
{
    private array $data;

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

    public function render(): string
    {
        return "<article><h2>{$this->data['title']}</h2><p>{$this->data['body']}</p></article>";
    }
}

class NewsContent implements ContentInterface
{
    private array $data;

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

    public function render(): string
    {
        return "<div class='news'><h3>{$this->data['headline']}</h3><p>{$this->data['summary']}</p></div>";
    }
}

class ContentFactory
{
    public static function create(string $type, array $data): ContentInterface
    {
        return match ($type) {
            'article' => new ArticleContent($data),
            'news' => new NewsContent($data),
            default => throw new \InvalidArgumentException("Unknown content type: $type"),
        };
    }
}

// Usage
$article = ContentFactory::create('article', ['title' => 'Hello', 'body' => 'World']);
echo $article->render();

XOOPS Database Factory

<?php
class XoopsDatabaseFactory
{
    public static function getDatabaseConnection()
    {
        static $instance;

        if (!isset($instance)) {
            $dbType = XOOPS_DB_TYPE ?? 'mysql';
            $className = 'XoopsDatabase' . ucfirst($dbType);

            if (!class_exists($className)) {
                $file = XOOPS_ROOT_PATH . '/class/database/' . strtolower($dbType) . '.php';
                if (file_exists($file)) {
                    require_once $file;
                }
            }

            $instance = new $className();

            if (!$instance->connect()) {
                trigger_error('Unable to connect to database', E_USER_ERROR);
            }
        }

        return $instance;
    }
}

Observer Pattern

The Observer pattern allows objects to be notified of changes to a subject’s state, enabling event-driven behavior.

When to Use

• Event handling
• Notification systems
• Plugin architectures
• Logging and auditing

Implementation

<?php
namespace XoopsModules\MyModule;

interface ObserverInterface
{
    public function update(string $event, array $data): void;
}

class EventDispatcher
{
    private array $observers = [];

    public function attach(string $event, ObserverInterface $observer): void
    {
        if (!isset($this->observers[$event])) {
            $this->observers[$event] = [];
        }

        $this->observers[$event][] = $observer;
    }

    public function detach(string $event, ObserverInterface $observer): void
    {
        if (isset($this->observers[$event])) {
            $key = array_search($observer, $this->observers[$event], true);
            if ($key !== false) {
                unset($this->observers[$event][$key]);
            }
        }
    }

    public function notify(string $event, array $data = []): void
    {
        if (isset($this->observers[$event])) {
            foreach ($this->observers[$event] as $observer) {
                $observer->update($event, $data);
            }
        }
    }
}

class EmailNotifier implements ObserverInterface
{
    public function update(string $event, array $data): void
    {
        if ($event === 'article.published') {
            // Send email notification
            $this->sendEmail($data['article']);
        }
    }

    private function sendEmail($article): void
    {
        $xoopsMailer = xoops_getMailer();
        $xoopsMailer->setSubject('New Article Published: ' . $article->getVar('title'));
        $xoopsMailer->setBody('A new article has been published.');
        $xoopsMailer->send();
    }
}

// Usage
$dispatcher = new EventDispatcher();
$dispatcher->attach('article.published', new EmailNotifier());

// When article is published
$dispatcher->notify('article.published', ['article' => $article]);

XOOPS Preloads (Observer Implementation)

modules/mymodule/preloads/core.php

<?php
class MymoduleCorePreload extends XoopsPreloadItem
{
    public static function eventCoreIncludeCommonEnd($args)
    {
        // React to core common include completing
        $GLOBALS['xoopsLogger']->addExtra('MyModule', 'Initialized');
    }

    public static function eventCoreHeaderEnd($args)
    {
        // Add custom headers
        $GLOBALS['xoTheme']->addStylesheet('modules/mymodule/assets/css/custom.css');
    }

    public static function eventCoreFooterStart($args)
    {
        // Execute before footer renders
    }
}

Decorator Pattern

The Decorator pattern adds behavior to objects dynamically without affecting other objects of the same class.

When to Use

• Form element customization
• Output formatting
• Permission checking
• Caching layers

Implementation

<?php
namespace XoopsModules\MyModule;

interface FormElementInterface
{
    public function render(): string;
}

class TextInput implements FormElementInterface
{
    private string $name;
    private string $value;

    public function __construct(string $name, string $value = '')
    {
        $this->name = $name;
        $this->value = $value;
    }

    public function render(): string
    {
        return sprintf(
            '<input type="text" name="%s" value="%s">',
            htmlspecialchars($this->name),
            htmlspecialchars($this->value)
        );
    }
}

abstract class FormElementDecorator implements FormElementInterface
{
    protected FormElementInterface $element;

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

    public function render(): string
    {
        return $this->element->render();
    }
}

class RequiredDecorator extends FormElementDecorator
{
    public function render(): string
    {
        return $this->element->render() . '<span class="required">*</span>';
    }
}

class LabelDecorator extends FormElementDecorator
{
    private string $label;

    public function __construct(FormElementInterface $element, string $label)
    {
        parent::__construct($element);
        $this->label = $label;
    }

    public function render(): string
    {
        return sprintf(
            '<label>%s</label>%s',
            htmlspecialchars($this->label),
            $this->element->render()
        );
    }
}

class HelpTextDecorator extends FormElementDecorator
{
    private string $helpText;

    public function __construct(FormElementInterface $element, string $helpText)
    {
        parent::__construct($element);
        $this->helpText = $helpText;
    }

    public function render(): string
    {
        return $this->element->render() . sprintf(
            '<small class="help-text">%s</small>',
            htmlspecialchars($this->helpText)
        );
    }
}

// Usage - decorators can be stacked
$input = new TextInput('username');
$input = new RequiredDecorator($input);
$input = new LabelDecorator($input, 'Username');
$input = new HelpTextDecorator($input, 'Enter your username');

echo $input->render();
// Output: <label>Username</label><input type="text" name="username" value=""><span class="required">*</span><small class="help-text">Enter your username</small>

Strategy Pattern

The Strategy pattern defines a family of algorithms, encapsulates each one, and makes them interchangeable.

When to Use

• Multiple authentication methods
• Different sorting algorithms
• Various export formats
• Flexible validation rules

Implementation

<?php
namespace XoopsModules\MyModule;

interface AuthStrategyInterface
{
    public function authenticate(string $username, string $password): bool;
}

class DatabaseAuthStrategy implements AuthStrategyInterface
{
    public function authenticate(string $username, string $password): bool
    {
        $memberHandler = xoops_getHandler('member');
        $user = $memberHandler->loginUser($username, $password);

        return $user !== false;
    }
}

class LdapAuthStrategy implements AuthStrategyInterface
{
    private string $ldapHost;
    private int $ldapPort;

    public function __construct(string $host, int $port = 389)
    {
        $this->ldapHost = $host;
        $this->ldapPort = $port;
    }

    public function authenticate(string $username, string $password): bool
    {
        $ldap = ldap_connect($this->ldapHost, $this->ldapPort);

        if (!$ldap) {
            return false;
        }

        $bind = @ldap_bind($ldap, "uid=$username,ou=users,dc=example,dc=com", $password);

        ldap_close($ldap);

        return $bind;
    }
}

class AuthService
{
    private AuthStrategyInterface $strategy;

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

    public function setStrategy(AuthStrategyInterface $strategy): void
    {
        $this->strategy = $strategy;
    }

    public function login(string $username, string $password): bool
    {
        return $this->strategy->authenticate($username, $password);
    }
}

// Usage
$authService = new AuthService(new DatabaseAuthStrategy());

// Can switch strategies at runtime
if ($useLdap) {
    $authService->setStrategy(new LdapAuthStrategy('ldap.example.com'));
}

$authenticated = $authService->login($username, $password);

Repository Pattern

The Repository pattern provides an abstraction layer between data access logic and business logic.

When to Use

• Complex data access requirements
• Multiple data sources
• Testable data layers
• Domain-Driven Design

Implementation

<?php
namespace XoopsModules\MyModule\Repository;

use XoopsModules\MyModule\Entity\Article;

interface ArticleRepositoryInterface
{
    public function find(int $id): ?Article;
    public function findBySlug(string $slug): ?Article;
    public function findPublished(int $limit = 10, int $offset = 0): array;
    public function save(Article $article): bool;
    public function delete(Article $article): bool;
}

class ArticleRepository implements ArticleRepositoryInterface
{
    private \XoopsPersistableObjectHandler $handler;

    public function __construct(\XoopsPersistableObjectHandler $handler)
    {
        $this->handler = $handler;
    }

    public function find(int $id): ?Article
    {
        $obj = $this->handler->get($id);
        return $obj ?: null;
    }

    public function findBySlug(string $slug): ?Article
    {
        $criteria = new \Criteria('slug', $slug);
        $objects = $this->handler->getObjects($criteria);

        return !empty($objects) ? $objects[0] : null;
    }

    public function findPublished(int $limit = 10, int $offset = 0): array
    {
        $criteria = new \CriteriaCompo();
        $criteria->add(new \Criteria('status', 'published'));
        $criteria->setSort('published_at');
        $criteria->setOrder('DESC');
        $criteria->setLimit($limit);
        $criteria->setStart($offset);

        return $this->handler->getObjects($criteria);
    }

    public function save(Article $article): bool
    {
        return $this->handler->insert($article);
    }

    public function delete(Article $article): bool
    {
        return $this->handler->delete($article);
    }
}

Dependency Injection

Dependency Injection (DI) allows objects to be constructed with their dependencies instead of creating them internally.

Benefits

• Improved testability
• Loose coupling
• Flexible configuration
• Better code organization

Implementation

<?php
namespace XoopsModules\MyModule;

class ArticleService
{
    private Repository\ArticleRepositoryInterface $repository;
    private CacheInterface $cache;
    private LoggerInterface $logger;

    public function __construct(
        Repository\ArticleRepositoryInterface $repository,
        CacheInterface $cache,
        LoggerInterface $logger
    ) {
        $this->repository = $repository;
        $this->cache = $cache;
        $this->logger = $logger;
    }

    public function getArticle(int $id): ?Entity\Article
    {
        $cacheKey = "article_{$id}";

        // Try cache first
        if ($this->cache->has($cacheKey)) {
            $this->logger->debug("Article {$id} loaded from cache");
            return $this->cache->get($cacheKey);
        }

        // Load from repository
        $article = $this->repository->find($id);

        if ($article) {
            $this->cache->set($cacheKey, $article, 3600);
            $this->logger->debug("Article {$id} loaded from database");
        }

        return $article;
    }
}

// Service container setup
$container = new DependencyContainer();

$container->register('db', fn() => XoopsDatabaseFactory::getDatabaseConnection());

$container->register('articleHandler', fn($c) =>
    new ArticleHandler($c->resolve('db'))
);

$container->register('articleRepository', fn($c) =>
    new Repository\ArticleRepository($c->resolve('articleHandler'))
);

$container->register('cache', fn() => new FileCache(XOOPS_VAR_PATH . '/caches'));

$container->register('logger', fn() => new XoopsLogger());

$container->register('articleService', fn($c) =>
    new ArticleService(
        $c->resolve('articleRepository'),
        $c->resolve('cache'),
        $c->resolve('logger')
    )
);

// Usage
$articleService = $container->resolve('articleService');
$article = $articleService->getArticle(1);

Best Practices

Pattern Selection Guidelines

1. Choose patterns based on actual needs, not anticipated ones
2. Keep implementations simple - don’t over-engineer
3. Document pattern usage for team understanding
4. Combine patterns when appropriate (e.g., Factory + Singleton)
5. Consider testability when selecting patterns

Common Anti-Patterns to Avoid

Anti-Pattern	Problem	Solution
God Object	Class does too much	Single Responsibility
Spaghetti Code	No clear structure	Use MVC pattern
Copy-Paste	Code duplication	Extract common code
Magic Numbers	Unclear constants	Use named constants
Tight Coupling	Hard to test/maintain	Use Dependency Injection

Testing Patterns

<?php
// Unit testing with dependency injection
class ArticleServiceTest extends \PHPUnit\Framework\TestCase
{
    private $repository;
    private $cache;
    private $logger;
    private $service;

    protected function setUp(): void
    {
        $this->repository = $this->createMock(ArticleRepositoryInterface::class);
        $this->cache = $this->createMock(CacheInterface::class);
        $this->logger = $this->createMock(LoggerInterface::class);

        $this->service = new ArticleService(
            $this->repository,
            $this->cache,
            $this->logger
        );
    }

    public function testGetArticleFromCache(): void
    {
        $article = new Article();
        $article->setVar('article_id', 1);

        $this->cache->expects($this->once())
            ->method('has')
            ->with('article_1')
            ->willReturn(true);

        $this->cache->expects($this->once())
            ->method('get')
            ->with('article_1')
            ->willReturn($article);

        $result = $this->service->getArticle(1);

        $this->assertSame($article, $result);
    }
}

Related Documentation

• XOOPS-Architecture - Overall system architecture
• Database Layer - Data persistence patterns
• Security Best Practices - Secure pattern implementation

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#xoops #design-patterns #architecture #mvc #singleton #factory #observer