Memoization is a common technique to avoid heavy computation by caching previous returned value.

This is a proposal to add #[Memoize] method attribute to Symfony in order to return a cached response using Cache
component. Actually more a POC than PR.

Proposed Usage:

#[Memoizable]
class MyService
{
    public function __construct(private readonly HttpClientInterface $client)
    {
    }

    #[Memoize(pool: 'cache.redis_pool', ttl: 5)]
    public function getSomeEndpoint(string $name): string
    {
        return $this->client->request('GET', '/api/some/endpoint')->getContent();
    }

    #[Memoize(pool: 'cache.pdo_pool', keyGenerator: CustomKeyGenerator::class, ttl: 3600)]
    public function getThatChangesRarely(string $name): string
    {
        return $this->client->request('GET', '/api/that/changes/rarely')->getContent();
    }
}

Questions:

Before going further (refactoring, adding tests, etc.), it could be a good thing to get some comments because
each solution could take a lot of time to implement :

• How the service is created
  • By replacing the current service by a factory which will create the "proxy" from extended class used in this
    PR. Final services won't be supported used in this PR due to ProxyManager.
  • By decorating the service (see last point). Interfaces have to be kept, all functions implemented and magic
    methods implemented to retrieve/call public properties/methods.
• How to generate and dump the file
  • By using the AccessInterceptorValueHolderFactory if ProxyManager bridge is installed used in this PR.
  • By using a Generator like AccessInterceptorValueHolderGenerator to generate the class and using a custom
    PhpDumper to save. Something similar as it's done for lazy services.
  • By generating manually, it can be a hard task to handle all specific cases.

Is it new?

A bundle already exists about memoization: https://github.com/RikudouSage/SymfonyMemoizeBundle but this PR differs:

• Cache can be configured (which cache, TTL, key generation).
• Generated classes use inheritance instead of decoration (for now, like lazy proxy does).