Allow injection of multibinding providers

[poletti-marco]

E.g. we could define a fruit::MultibindingProvider<T> class that allows to get a vector of the multibindings for that type, and allow injecting that as a dependency.
This will have the caveat that injection dependency loops involving a MultibindingProvider will only be detected at runtime.

To print the actual loop, maybe we can have an on-this-error-only, slow code path where we walk the injection graph at runtime, looking for in-progress injections, to find the loop; then we can print a more useful error message with the types involved in the loop. TBD if there's enough information available to determine the loop.

[Inujel]

Is this the missing piece to achieve something like this?

class Service{};
class A : public Service{};
class B : public Service{};

class App
{
public:
   INJECT(App(std::vector<Service*> services)) {}
};

fruit::Component<App> app_component()
{
   return fruit::createComponent()
		.addMultibinding<Service, A>()
		.addMultibinding<Service, B>();
}

Or is it already doable and I'm missing something?

[poletti-marco]

Hi, sorry for the delay.
Yes, exactly.
ATM you need to get the multi binders from the injector directly then pass them down to the method/object that needs them.