Registration ordering

[chrath]

We would like to use get_it for our project, but we are confused how the registration process works. Did we understand the documentation correctly that we need to register the dependencies manually in the correct order?

Let's say we have a ServiceA and ServiceB which depends on ServiceA. We then manually need to make sure that we first register ServiceA before we register ServiceB?

// this works
_getIt.registerSingleton<ServiceA>(ServiceA());
_getIt.registerSingleton<ServiceB>(ServiceB(_getIt<ServiceA>));

// this results in a type ServiceA is not registered inside GetIt.
_getIt.registerSingleton<ServiceB>(ServiceB(_getIt<ServiceA>));
_getIt.registerSingleton<ServiceA>(ServiceA());

Our previous IoC container was able to resolve the dependencies automatically. If we switch to get_it, we would have to manually reorder about a hundred dependencies. Even once the dependencies are ordered, each new dependency registration must also be in the right place. With many dependencies, this can be quite difficult to maintain.

Is this a current limitation of get_it or did we misunderstand the documentation? And do you know a strategy how to deal with this kind of issue? Anyways, thanks for your great work!

[mozerrr]

You can use registerSingletonWithDependencies, check docs here.

[escamoteur]

In general, yes you have to ensure the corrcect sequence of registration. there is support to esure that asynchronous created objects are available before other objects need to acces them but they have to be registered in the correct sequence.
Without Reflection I think it's not really possible to avoid that.
Which IoC container did you use?

[chrath]

Thanks for your reply. We are currently using this package here: https://pub.dev/packages/flutter_simple_dependency_injection. I don't know in detail how it works, but we do not need to care about the ordering of registrations.

[escamoteur]

I think I understand the difference now. Your other package uses always factory functions which means that you can't run into a dependency problem while you register all your types. If you register all your types as lazySingletons you should get the same behavior.

[chrath]

Thanks for the explanation. We'll have a look and try the lazySingletons. Thanks for you help!