[DI] Allow using a class factory #23819

GuilhemN · 2017-08-07T14:55:55Z

Q	A
Bug report?	no
Feature request?	yes
BC Break report?	no
RFC?	yes
Symfony version	3.4

Here's a proposal coming mostly from @nicolas-grekas (I helped a bit making the example :)).
Would you like to be able use a class factory to define your services?

Main benefits:

service names based on the methods return type (or @Alias)
arguments injection based on autowiring
access to php functions at runtime (no need anymore of the expression language), that also means access to getenv()
possibility to manually inline simple services

An example of how it could be used:

// services.yaml
imports:
    - type: service_factory
      resource: App\MyServicesFactory

// src/MyServicesFactory.php
<?php

namespace App;

use App\Entity\Product;
use Doctrine\Bundle\DoctrineBundle\Registry;
use Psr\Logger\LoggerInterface;

class MyServicesFactory
{
    private static $apiKey = 'foo';
    private $database;

    public function __construct()
    {
        // Constructor called with *no* argument
    }

    /**
     * @Tag(name="monolog.logger", channel="my_channel")
     * @Alias(id="my_service")
     * @Alias // when used with no id, the return type is used
     * @Param("strategies", tag="app.strategies")
     * 
     * @param StrategyInterface[] $strategies // it's the responsibility of a DI extension to populate this
     */
    public function myService(LoggerInterface $logger, iterable $strategies): MyServiceInterface
    {
      	$myService = new MyService($logger);
      	$myService->setSecret(self::$apiKey); // the service can be easily configured
      	$myService->setSecret(getenv('API_KEY')); // even dynamically
      	foreach ($strategies as $strategy) {
            $myService->addStrategy();
     	}

    	// Less flexible than an injected dep, but still a nice shortcut for private apps
        // benefits from type hinting (return type vs argument type can be verified by IDEs)
      	$myService->setDatabase($this->myDatabase()); 
  
      	return $myService;
    }

    /**
     * ExpressionLanguage not needed anymore.
     */
    public function myController(MyService $myService, Repository $doctrine): MyController
    {
      	return new MyController($myService, $doctrine->getRepository(Product::class));
    }

    protected function myDatabase(): DatabaseInterface
    {
      	return $this->database ?? $this->database = new Database('dns://...');
    }
}

Wdyt? This could be an alternative to #22407.

The text was updated successfully, but these errors were encountered:

nicolas-grekas · 2017-08-07T14:59:29Z

Disclaimer: this borrows some ideas from Disco :)
And I think it has more potential than #22407 because it allows writting code that is actually used at runtime (vs a DSL-like - which is nice BTW!)

sstok · 2017-08-08T10:12:26Z

Interesting, wondering would this also make https://github.com/container-interop/service-provider also easier to realize?

shochdoerfer · 2017-08-08T20:26:20Z

Almost as good as Disco :) I like the idea of passing dependencies via method parameter, that solves quite a bit of the magic within Disco that I do not really like.

Are you able to register multiple factories? If so, how would you solve naming collisions?

GuilhemN · 2017-08-08T20:32:33Z

@sstok I don't think so, the implementation is different.

Are you able to register multiple factories? If so, how would you solve naming collisions?

@shochdoerfer yes, that's just a resource. About conflicts, I'd say like right now, the latest service defined wins.

Tobion · 2017-08-08T23:31:59Z

I really like this proposal.

It uses normal PHP code and does not require another format/language you need to learn, e.g. compared to [DI] Add a new "PHP fluent format" for configuring the container #22407
Sometimes initializing services isn't that straightforward, e.g. Guzzle clients with complicated middlewares. So at first you think how to do it in PHP. And then you still have to transcode that to yaml or xml which doesn't make it easier. With this proposal you just have to do it once in PHP with a factory and you're set.

shochdoerfer · 2017-08-09T06:46:41Z

@nicolas-grekas Any chance to join forces with Disco? Like extending Disco to be able to use it as a common basis? Ping me if you are interested...

fabpot · 2017-08-10T05:54:57Z

For the record, #23834 looks much better to me.

ro0NL · 2017-08-16T14:33:14Z

@GuilhemN what about favoring #23834 for annotating. So the factory would implement i.e. ServiceFactoryInterface and have a static method that receives a id + definition configurator for each class method.

The factory itself is also a service.

chalasr · 2017-09-30T20:07:05Z

Is this still relevant?

nicolas-grekas · 2017-09-30T21:07:39Z

Closing as I think we drafted the idea, so can be referenced in the future when needed.

xabbuh added DependencyInjection Feature labels Aug 7, 2017

Tobion mentioned this issue Aug 9, 2017

[DI] Add "PHP fluent format" for configuring the container #23834

Merged

ro0NL mentioned this issue Aug 19, 2017

[DI] Add PHP service factories #23935

Closed

nicolas-grekas closed this as completed Sep 30, 2017

nicolas-grekas mentioned this issue Dec 11, 2018

[DependencyInjection] Request for anonymous function factories #28992

Closed

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

[DI] Allow using a class factory #23819

[DI] Allow using a class factory #23819

[DI] Allow using a class factory #23819

[DI] Allow using a class factory #23819

Comments