Refactoring with Rector

As big codebases age they often struggle to keep up with changes to programming languages and package development. New language features can't be easily adopted, and packages are often stuck on an old version due to a backwards-incompatible change. Fixing this requires large scale refactoring which can often take hundreds of hours. Why not automate it?

In this talk we'll look at Rector, a PHP refactoring tool that automates hundreds of different refactorings. We'll look at different use cases, writing our own refactorings, and even converting an entire project from one framework to another!

Transcript

1. Refactoring with Rector Glynn Forrest glynn@backbeat.tech @glynn_forrest
2. @glynn_forrest Overview • Why we refactor • How Rector can help • Custom Rectors • How it works • Recommendations • Demo
3. @glynn_forrest Code is a liability
4. @glynn_forrest Code is a liability • Without care, your codebase will rot • Packages and frameworks have deprecations and breaking changes • Upgrading a large codebase takes time • Bad code sneaks in, very rarely leaves • Quick fixes / cludges
5. @glynn_forrest Refactoring
6. @glynn_forrest Easy wins • Linting ◦ jakub-onderka/php-parallel-lint ◦ squizlabs/php_codesniffer ◦ friendsofphp/php-cs-fixer --dry-run • Static analysis ◦ phpstan/phpstan ◦ vimeo/psalm ◦ phan/phan • Run these in your CI builds
7. @glynn_forrest Easy wins • Review all new code
8. @glynn_forrest Harder problems
9. @glynn_forrest Harder problems Upgrading PHP versions
10. @glynn_forrest Harder problems Fixing worn out code
11. @glynn_forrest Harder problems Framework deprecations
12. @glynn_forrest Rector solves this for you
13. @glynn_forrest Rector solves this for you • “Upgrade your Legacy App to Modern Codebase” ◦ “Rector is a reconstructor tool - it does instant upgrades and instant refactoring of your code.” • github.com/rectorphp/rector • getrector.org
14. @glynn_forrest But what is it? • Command line tool to automatically modify PHP code • The ‘process’ command runs various transformations (Rectors) • Configured with a YAML file • Has built in configurations called ‘sets’
15. @glynn_forrest Install • As a dev package • Docker image • Separate repository for a group of projects
16. @glynn_forrest First steps • Pick a basic rector • Create a simple rector.yaml • Run on a directory of code • Review diff
17. @glynn_forrest With arguments • Some Rectors have arguments • Symfony services configuration with a tweak
18. @glynn_forrest With arguments • Based on Symfony’s DI component • Magic performed by compiler passes • Extends argument handling to be less verbose
19. @glynn_forrest More examples FacadeStaticCallToConstructorInjectionRector
20. @glynn_forrest More examples FormIsValidRector
21. @glynn_forrest Sets • Premade config files for a specific use case • Upgrade PHP versions • Upgrade framework package versions • Fix deprecated usages • Best practices
22. @glynn_forrest Sets PHPUnit 8 had some unpopular breaking changes
23. @glynn_forrest Sets Fixed in seconds with the phpunit80 set
24. @glynn_forrest Sets Upgrade Symfony version CHANGELOG.md and UPGRADE.md as Rectors
25. @glynn_forrest Sets Change an entire Laravel project from static method calls to dependency injection
26. @glynn_forrest Sets Change frameworks...
27. @glynn_forrest Sets Still just a combination of Rectors
28. @glynn_forrest Other config • Tweak autoloading paths • Classes must be autoload-able • Command line flag or config file
29. @glynn_forrest Other config • Skip files or directories • Use language features of a specific PHP version • Skip specific rules in a set
30. @glynn_forrest Custom Rectors
31. @glynn_forrest Custom Rectors Simply implement PhpRectorInterface and register it as a service
32. @glynn_forrest Custom Rectors Extend AbstractRector and write 3 methods
33. @glynn_forrest Custom Rectors getDefinition() for documentation
34. @glynn_forrest Custom Rectors getNodeTypes() for the parts of the syntax tree changed by this Rector See rector/docs/NodesOverview.md
35. @glynn_forrest Custom Rectors refactor() to return a changed Node (null for no change)
36. @glynn_forrest Custom Rectors Add to a rector config file and run
37. @glynn_forrest Architecture
38. @glynn_forrest Architecture • Uses nikic/php-parser and phpstan/phpstan to analyse and manipulate the code • Glued together with Symfony packages (console, dependency injection, finder, yaml, etc) • Yaml file is Symfony services config (services, parameters, imports) • Rectors are only used when registered as services
39. @glynn_forrest Architecture
40. @glynn_forrest Recommendations
41. @glynn_forrest Recommendations • Use the code-quality and dead-code sets for an easy win on an old codebase • Also consider the coding-style set
42. @glynn_forrest Recommendations • Write your own Rector for any non-trivial change across a large codebase • Consistency • Next time will be easier
43. @glynn_forrest Recommendations • Don’t name your config file rector.yaml • Principle of least surprise • Running with --set will also include the rules in the config file
44. @glynn_forrest Recommendations • Browse a specific tag on Github • Rector moves very fast • Default branch is master
45. @glynn_forrest A note from our sponsors
46. @glynn_forrest Sponsorship • Tomáš is a volunteer • patreon.com/rectorphp
47. @glynn_forrest DEMO