How to Increase Code Quality in PHP

PHP remains one of the most widely-used programming languages for web development, powering platforms like WordPress, Drupal, OpenCart and Magento. However, with its flexibility comes the risk of messy, hard-to-maintain code. Ensuring high-quality PHP code is essential for creating reliable, efficient, and scalable applications.

Follow Coding Standards

Adhering to a consistent coding standard is foundational to code quality. The PHP-FIG (Framework Interoperability Group) recommends PSR standards, such as:

• PSR-1: Basic coding standard.
• PSR-12: Extended coding style guide.

Using tools like PHP CodeSniffer can help enforce these standards in your projects.

Example:

// Bad example
function calculate($val1,$val2){return $val1+$val2;}

// Good example (PSR-12 compliant)
function calculate(int $value1, int $value2): int
{
    return $value1 + $value2;
}

Leverage Type Declarations

PHP supports type declarations for function arguments and return values, which help catch errors early and improve code readability.

Example:

// Before PHP 7
function add($a, $b)
{
    return $a + $b;
}

// With type declarations
function add(int $a, int $b): int
{
    return $a + $b;
}

Type safety ensures your code behaves predictably and is easier to debug.

Write Unit Tests

Unit tests ensure individual components of your application work as intended. Frameworks like PHPUnit make it simple to create and run tests. Writing tests may seem time-consuming, but it saves debugging time and reduces regressions in the long run.

Example:

use PHPUnit\Framework\TestCase;

class CalculatorTest extends TestCase
{
    public function testAddition()
    {
        $calc = new Calculator();
        $this->assertEquals(5, $calc->add(2, 3));
    }
}

Use Static Analysis Tools

Static analysis tools analyze your code without executing it, identifying potential bugs and violations of best practices. Popular options include:

• PHPStan: Focuses on static analysis.
• Psalm: Integrates well with large codebases.
• Phan: Good for legacy codebases.

These tools highlight issues like unused variables, incorrect types, or undefined methods.

Employ Dependency Injection

Avoid creating dependencies inside classes. Instead, inject them through constructors or setters. This approach improves code modularity and testability.

Example:

// Bad example
class UserController
{
    public function __construct()
    {
        $this->service = new UserService();
    }
}

// Good example
class UserController
{
    private UserService $service;

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

Refactor Regularly

Refactoring keeps your codebase clean and manageable. Apply principles like:

• DRY (Don’t Repeat Yourself): Eliminate duplicate code.
• SOLID: Follow object-oriented design principles.
• KISS (Keep It Simple, Stupid): Avoid overcomplicating.

Use tools like PHP Refactoring Browser or IDE-integrated features to assist in this process.

Utilize Composer for Dependency Management

Composer simplifies dependency management by letting you declare the libraries your project needs. It also ensures you’re using the latest stable versions of dependencies.

Example:

composer require monolog/monolog

Define dependencies in the composer.json file and run composer update to keep them updated.

Automate Code Quality Checks

Set up automated tools to maintain consistent quality throughout development. Popular CI/CD tools like GitHub Actions, GitLab CI, or Jenkins can integrate with linters, static analyzers, and test suites to catch issues before deployment.

Example GitHub Actions Workflow:

name: PHP Code Quality

on: [push, pull_request]

jobs:
  lint-and-test:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v3
      - name: Set up PHP
        uses: shivammathur/setup-php@v2
        with:
          php-version: 8.1
          tools: composer, phpstan, php-cs-fixer

      - name: Install dependencies
        run: composer install --prefer-dist --no-progress

      - name: Run PHPStan
        run: vendor/bin/phpstan analyse

      - name: Run PHPUnit
        run: vendor/bin/phpunit

Document Your Code

Well-documented code is easier to understand and maintain. Use PHPDoc to describe methods, parameters, and return types.

Example:

/**
 * Calculates the sum of two numbers.
 *
 * @param int $a First number.
 * @param int $b Second number.
 * @return int Sum of the numbers.
 */
function add(int $a, int $b): int
{
    return $a + $b;
}

Improving code quality in PHP is a continuous process that involves adhering to standards, leveraging modern tools, and adopting best practices. By implementing the strategies outlined above, you can build cleaner, more reliable, and maintainable applications.