Reason for not using absolute paths in file loader

[ruudk]

I'm wondering: What is the reason for not allowing absolute paths in the FilesytemLoader? Also, why are relative paths (starting with ./) not supported? Why do we have to use the path namespaces?

This is not a complaint, just something that I want to try to understand. There is probably a good reason for this 😊

[fabpot]

The main reason is reproducible builds and the possibility to move the cache around.

[ruudk]

Thanks.

I needed a way to analyze Twig templates locally, that don't require builds / caching. I ended up creating an AbsolutePathLoader. For anyone that's interested in this:

use Twig\Loader\FilesystemLoader;
use Twig\Loader\LoaderInterface;
use Twig\Source;

final readonly class AbsolutePathLoader implements LoaderInterface
{
    public function __construct(
        private FilesystemLoader $loader,
    ) {}

    private function maybeResolveAbsolutePath(string $name) : string
    {
        foreach ($this->loader->getNamespaces() as $namespace) {
            foreach ($this->loader->getPaths($namespace) as $path) {
                if (str_starts_with($name, $path)) {
                    return sprintf('@%s/%s', $namespace, substr($name, strlen($path)));
                }
            }
        }

        return $name;
    }

    public function getSourceContext(string $name): Source
    {
        return $this->loader->getSourceContext($this->maybeResolveAbsolutePath($name));
    }

    public function getCacheKey(string $name): string
    {
        return $this->loader->getCacheKey($this->maybeResolveAbsolutePath($name));
    }

    public function isFresh(string $name, int $time): bool
    {
        return $this->loader->isFresh($this->maybeResolveAbsolutePath($name), $time);
    }

    public function exists(string $name)
    {
        return $this->loader->exists($this->maybeResolveAbsolutePath($name));
    }
}