forked from https://github.com/symfony/symfony
539f4ca162
This PR was merged into the 4.3-dev branch.
Discussion
----------
[DI] Add support for "wither" methods - for greater immutable services
| Q | A
| ------------- | ---
| Branch? | master
| Bug fix? | no
| New feature? | yes
| BC breaks? | no
| Deprecations? | no
| Tests pass? | yes
| Fixed tickets | -
| License | MIT
| Doc PR | https://github.com/symfony/symfony-docs/pull/10991
Let's say we want to define an immutable service while still using traits for composing its optional features. A nice way to do so without hitting [the downsides of setters](https://symfony.com/doc/current/service_container/injection_types.html#setter-injection) is to use withers. Here would be an example:
```php
class MyService
{
use LoggerAwareTrait;
}
trait LoggerAwareTrait
{
private $logger;
/**
* @required
* @return static
*/
public function withLogger(LoggerInterface $logger)
{
$new = clone $this;
$new->logger = $logger;
return $new;
}
}
$service = new MyService();
$service = $service->withLogger($logger);
```
As you can see, this nicely solves the setter issues.
BUT how do you make the service container create such a service? Right now, you need to resort to complex gymnastic using the "factory" setting - manageable for only one wither, but definitely not when more are involved and not compatible with autowiring.
So here we are: this PR allows configuring such services seamlessly.
Using explicit configuration, it adds a 3rd parameter to method calls configuration: after the method name and its parameters, you can pass `true` and done, you just declared a wither:
```yaml
services:
MyService:
calls:
- [withLogger, ['@logger'], true]
```
In XML, you could use the new `returns-clone` attribute on the `<call>` tag.
And when using autowiring, the code looks for the `@return static` annotation and turns the flag on if found.
There is only one limitation: unlike services with regular setters, services with withers cannot be part of circular loops that involve calls to wither methods (unless they're declared lazy of course).
Commits
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| .composer | ||
| .github | ||
| src/Symfony | ||
| .appveyor.yml | ||
| .editorconfig | ||
| .gitignore | ||
| .php_cs.dist | ||
| .travis.yml | ||
| CHANGELOG-4.0.md | ||
| CHANGELOG-4.1.md | ||
| CHANGELOG-4.2.md | ||
| CODE_OF_CONDUCT.md | ||
| composer.json | ||
| CONTRIBUTING.md | ||
| CONTRIBUTORS.md | ||
| LICENSE | ||
| link | ||
| phpunit | ||
| phpunit.xml.dist | ||
| README.md | ||
| UPGRADE-4.0.md | ||
| UPGRADE-4.1.md | ||
| UPGRADE-4.2.md | ||
| UPGRADE-4.3.md | ||
| UPGRADE-5.0.md | ||
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