New in Rector 0.12 - Introducing Rector Config with Autocomplete

A year ago we switched to a distribution repository releases. It now allows us to add own RectorConfig class on top of Symfony internals.

The RectorConfig helps you by:

• full IDE autocomplete,
• isolation from Symfony - useful for Symfony projects
• validation of configuration methods that happens before running Rector itself

Are you curious about the implementation? In the end, the secret is in a single patched file with 4 changed lines.

So what does it look like?

Configuration as we Know It Now

use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;
use Rector\Configuration\Option;
use Rector\DowngradePhp81\Rector\Property\DowngradeReadonlyPropertyRector;

// ups, possible conflict with ContainerConfigurator
return static function (ContainerConfigurator $containerConfigurator): void {
    $parameters = $containerConfigurator->parameters();

    // too verbose params, constants and possible typo in param value
    $parameters->set(Option::PATHS, [[ // ups, "[[" typo
        __DIR__ . '/src/',
    ]]);

    $services = $containerConfigurator->services();
    $services->set(DowngradeReadonlyPropertyRector::class);
};

Such complexity is confusing just to read and easy to make error in.

The new Way to Configure Rector

What if we could single class to configure the Rector?

use Rector\Config\RectorConfig;

return static function (RectorConfig $rectorConfig): void {
    $rectorConfig->parallel();

    $rectorConfig->paths([
        __DIR__.'/src',
    ]);

    $rectorConfig->rule(DowngradeReadonlyPropertyRector::class);
};

How to upgrade to RectorConfig?

First, be sure to use at least Rector 0.12.21. If your config has a few lines, you can handle it easily manually. But what if you have dozens of lines or even custom configs in your tests? Rector to the rescue!

use Rector\Config\RectorConfig;
use Rector\Set\ValueObject\SetList;

return static function (RectorConfig $rectorConfig): void {
    $rectorConfig->sets([
        SetList::RECTOR_CONFIG
    ]);
};

Do you use Symfony? Avoid converting your Symfony /configs and only process only your Rector configs:

vendor/bin/rector process rector.php utils/rector/tests

Thanks to this upgrade set, we've migrated all the Rector packages to use the new RectorConfig syntax.

Configured Rules

Do you configure your rules? In previous version we've added configure() method to help with validation of configuration:

use Rector\Renaming\Rector\Name\RenameClassRector;
use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;

return static function (ContainerConfigurator $containerConfigurator): void {
    $services = $containerConfigurator->services();
    $services->set(RenameClassRector::class)
        ->configure([
            'App\SomeOldClass' => 'App\SomeNewClass',
        ]);

But it was not enough, was it?

That's why now you can use dedicated ruleWithConfiguration() method with validated input:

use Rector\Renaming\Rector\Name\RenameClassRector;
use Rector\Config\RectorConfig;

return static function (RectorConfig $rectorConfig): void {
    $rectorConfig->ruleWithConfiguration(RenameClassRector::class, [
        'App\SomeOldClass' => 'App\SomeNewClass',
    ]);

Why not just use the rule() method with a magic 2nd argument? The reason to separate these 2 methods is to give you fast feedback about wrong configuration:

• when you try to rule without configuration, e.g., ChangeSwitchToMatchRector with configuration, Rector will tell you the configuration is not needed
• and when you use a rule that requires configuration, e.g., RenameClassRector, you'll know about missing configuration too

Happy coding!