Code Smells in XOOPS Development

Overview

Code smells are indicators of potential problems in code. They don’t necessarily mean the code is broken, but they suggest areas that could benefit from refactoring.

Common Code Smells

flowchart TD
    A[Code Smell Detected] --> B{Type?}
    B --> C[Bloaters]
    B --> D[Object-Orientation Abusers]
    B --> E[Change Preventers]
    B --> F[Dispensables]
    B --> G[Couplers]

    C --> C1[Long Method]
    C --> C2[Large Class]
    C --> C3[Long Parameter List]

    D --> D1[Switch Statements]
    D --> D2[Temporary Field]

    E --> E1[Divergent Change]
    E --> E2[Shotgun Surgery]

    F --> F1[Dead Code]
    F --> F2[Duplicate Code]

    G --> G1[Feature Envy]
    G --> G2[Inappropriate Intimacy]

Bloaters

Long Method

// Smell: Method does too much
function processArticleSubmission($data) {
    // 100+ lines of validation, saving, notification, etc.
}

// Solution: Extract into focused methods
function processArticleSubmission(array $data): Article
{
    $this->validateInput($data);
    $article = $this->createArticle($data);
    $this->saveArticle($article);
    $this->notifySubscribers($article);
    return $article;
}

Large Class (God Object)

// Smell: Class does everything
class ArticleManager {
    public function create() { ... }
    public function delete() { ... }
    public function sendEmail() { ... }
    public function generatePDF() { ... }
    public function exportToExcel() { ... }
    public function validateUser() { ... }
    public function checkPermissions() { ... }
    // ... 50 more methods
}

// Solution: Split into focused classes
class ArticleService { ... }
class ArticleExporter { ... }
class ArticleNotifier { ... }
class PermissionChecker { ... }

Long Parameter List

// Smell: Too many parameters
function createArticle($title, $content, $author, $category, $tags, $status, $publishDate, $featured, $image) { ... }

// Solution: Use parameter object
class CreateArticleCommand {
    public string $title;
    public string $content;
    public int $authorId;
    public int $categoryId;
    public array $tags;
    public string $status;
    public ?DateTime $publishDate;
    public bool $featured;
    public ?string $image;
}

function createArticle(CreateArticleCommand $command): Article { ... }

Object-Orientation Abusers

Switch Statements

// Smell: Type checking with switch
function getDiscount($userType) {
    switch ($userType) {
        case 'regular':
            return 0;
        case 'premium':
            return 10;
        case 'vip':
            return 20;
        default:
            return 0;
    }
}

// Solution: Use polymorphism
interface UserType {
    public function getDiscount(): int;
}

class RegularUser implements UserType {
    public function getDiscount(): int { return 0; }
}

class PremiumUser implements UserType {
    public function getDiscount(): int { return 10; }
}

class VipUser implements UserType {
    public function getDiscount(): int { return 20; }
}

Temporary Field

// Smell: Fields only used in certain situations
class Article {
    private $tempCalculatedScore;

    public function search($terms) {
        $this->tempCalculatedScore = $this->calculateScore($terms);
        // ... use score
    }
}

// Solution: Pass as parameter or return value
class Article {
    public function getSearchScore(array $terms): float {
        return $this->calculateScore($terms);
    }
}

Change Preventers

Divergent Change

// Smell: One class changed for many different reasons
class Article {
    public function save() { ... } // Database change
    public function toJson() { ... } // API format change
    public function validate() { ... } // Business rule change
    public function render() { ... } // UI change
}

// Solution: Separate responsibilities
class Article { ... } // Domain object only
class ArticleRepository { public function save() { ... } }
class ArticleSerializer { public function toJson() { ... } }
class ArticleValidator { public function validate() { ... } }

Shotgun Surgery

// Smell: One change requires many file edits
// Changing date format requires editing:
// - ArticleController.php
// - ArticleView.php
// - ArticleAPI.php
// - ArticleExport.php

// Solution: Centralize
class DateFormatter {
    public function format(DateTime $date): string {
        return $date->format($this->config->get('date_format'));
    }
}

Dispensables

Dead Code

// Smell: Unreachable or unused code
function processData($data) {
    if (true) {
        return $this->handleData($data);
    }
    // This never executes
    return $this->legacyHandler($data);
}

// Old unused method still in codebase
function oldMethod() {
    // Not called anywhere
}

// Solution: Remove dead code
function processData($data) {
    return $this->handleData($data);
}

Duplicate Code

// Smell: Same logic in multiple places
class ArticleHandler {
    public function getActive() {
        $criteria = new CriteriaCompo();
        $criteria->add(new Criteria('status', 'active'));
        return $this->getObjects($criteria);
    }
}

class NewsHandler {
    public function getActive() {
        $criteria = new CriteriaCompo();
        $criteria->add(new Criteria('status', 'active'));
        return $this->getObjects($criteria);
    }
}

// Solution: Extract common behavior
trait ActiveRecordsTrait {
    public function getActive(): array {
        $criteria = new CriteriaCompo();
        $criteria->add(new Criteria('status', 'active'));
        return $this->getObjects($criteria);
    }
}

Couplers

Feature Envy

// Smell: Method uses another object's data more than its own
class Invoice {
    public function calculateTotal(Customer $customer) {
        $total = 0;
        foreach ($this->items as $item) {
            $total += $item->price;
        }
        // Uses customer data extensively
        if ($customer->isPremium()) {
            $total *= (1 - $customer->getDiscountRate());
        }
        if ($customer->getCountry() === 'US') {
            $total *= 1.08; // Tax
        }
        return $total;
    }
}

// Solution: Move behavior to the object with the data
class Customer {
    public function applyDiscount(float $amount): float {
        return $this->isPremium()
            ? $amount * (1 - $this->discountRate)
            : $amount;
    }

    public function applyTax(float $amount): float {
        return $this->country === 'US'
            ? $amount * 1.08
            : $amount;
    }
}

Refactoring Checklist

When you spot a code smell:

1. Identify - What smell is it?
2. Assess - How severe is the impact?
3. Plan - What refactoring technique applies?
4. Test - Ensure tests exist before refactoring
5. Refactor - Make small, incremental changes
6. Verify - Run tests after each change

Related Documentation

• Clean Code Principles
• Code Organization
• Testing Best Practices