How can you enforce design patterns and best practices in PHP applications with PHPMD?

1 What is PHPMD?

PHPMD is a static code analysis tool that scans your PHP files and detects various types of issues, such as potential bugs, code smells, complexity, naming, unused code, and more. PHPMD can help you improve your code quality by identifying and eliminating these problems before they cause errors, inefficiencies, or security risks. PHPMD is based on the well-known Java tool PMD, and supports several coding standards and rulesets, such as PSR-1, PSR-2, PSR-12, Symfony, Zend, and others.

2 How to install and use PHPMD?

There are several ways to install and use PHPMD, depending on your preferences and environment. You can install it globally using Composer, the PHP package manager, or download it as a PHAR file, a self-contained executable archive. You can also integrate it with your IDE, such as PhpStorm, Eclipse, or Visual Studio Code, or with your build system, such as Ant, Phing, or Grunt. You can run PHPMD from the command line, passing the path of the directory or file you want to analyze, the output format (text, XML, HTML, etc.), and the ruleset you want to apply. For example, to check your src folder using the PSR-2 ruleset and output the results in text format, you can run: phpmd src text psr2

3 How to configure and customize PHPMD?

PHPMD allows you to configure and customize its behavior and rules using XML files. You can create your own ruleset file, where you can specify which rules you want to enable or disable, and what parameters you want to use for each rule. For example, you can change the minimum number of lines for a method to be considered too long, or the maximum number of parameters for a function to be considered too complex. You can also create your own custom rules, using PHP or XPath expressions, to check for specific conditions or patterns in your code. You can then reference your ruleset or custom rule file when running PHPMD.

4 How to interpret and act on PHPMD results?

PHPMD will output a list of violations, each with a file name, a line number, a rule name, and a description. For example, you might see something like this: /src/Controller/UserController.php:23 The class UserController has 15 public methods and attributes. Consider reducing the number of public items to less than 10. This means that PHPMD has detected that your UserController class has too many public members, which can indicate a violation of the single responsibility principle or a lack of cohesion. You should consider refactoring your class to split it into smaller and more focused classes, or to make some of the members private or protected.

5 How to integrate PHPMD with other tools?

PHPMD can work well with other tools that can enhance your PHP development workflow and quality assurance. For example, you can use PHP_CodeSniffer, another static analysis tool, to check your code for syntax and style errors, and complement PHPMD's rules with more specific and detailed checks. You can also use PHPUnit, the most popular testing framework for PHP, to write and run unit tests for your code, and verify that it works as expected and does not introduce any regressions. You can also use PHPStan, a static type analysis tool, to check your code for type errors, and catch potential bugs that PHPMD might miss.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?