Support policy factories

[robertpustulka]

I have a case where my ORM policies need some dependencies. I'd like to pull those from a DIC. I was thinking that it may be a good idea to add support for policy factories. The feature might be useful with an upcoming core DIC support.

How this may work?

interface PolicyFactoryInterface
{
    public function create(string $className): object;
}

class DefaultPolicyFactory implements PolicyFactoryInterface
{
    public function create(string $className): object
    {
        return new $className;
    }
}

class OrmResolver implements ResolverInterface
{
    public function setFactory(PolicyFactoryInterface $factory): void
    {
        $this->policyFactory = $factory;
    }

    protected function getFactory(): PolicyFactoryInterface
    {
        if (!$this->policyFactory) {
            $this->policyFactory = new DefaultPolicyFactory;
        }
        return $this->policyFactory;
    }

    protected function findPolicy(string $class, string $name, string $namespace)
    {
        ...

        return new $this->getFactory()->create($policyClass);
    }
}

We would need to update all resolvers to use a factory internally, but with an optional setter injection this should be BC.

[markstory]

Would getting the resolvers from the DIC allow you to inject the required dependencies/container into the resolver as needed? Or are you trying to solve for built-in resolvers needing to have additional dependencies when creating policies? I ask because resolvers are already a factory for policies in many ways.

[robertpustulka]

Resolvers now do two things: they find the policy class and then create the policy object. I'd like to seperate those responsibilities in a way that extending built in resolvers would be easier when DIC comes in.

In my case the policy class need dependiencies. I'd like to avoid making the resolver dependent on a DIC, making the instantiation process transparent to the resolver and reusable across resolvers.

[markstory]

Ok. Then a factory makes sense.

[robertpustulka]

Should this be implemented for 2.x first and then backported to 1.x or implemented for 1.x and then merged into 2.x?

[markstory]

Doing the change for 2.x and backporting is probably easier as we won't miss typehints.

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