IoC container doesn't always respect .InSingletonScope()

[FaustoNascimento]

Take the following ConfigureIoC() code:

builder.Bind<Mercedes>().ToSelf().InSingletonScope();
builder.Bind<ICar>().ToAllImplementations();

When retrieving them as follows:

Container.Get<Mercedes>();
(Mercedes) Container.GetAll<ICar>().FirstOrDefault(x => x is Mercedes);

We end up with two distinct instances of Mercedes despite the fact that Mercedes was configured in singleton scope.

[canton7]

As discussed on IRC, this is because the binding of Mercedes to itself is a singleton. The binding of Mercedes to an ICar instance in the IEnumerable<ICar> is not.

You'll get the same with:

Bind<Mercedes>().ToSelf().InSingletonScope();
Bind<ICar>().To<Mercedes>().InSingletonScope();

container.Get<ICar>() == container.Get<Mercedes>(); // False

builder.Bind<Mercedes>().ToSelf().InSingletonScope(); does not mean "Whenever any instance of Mercedes is created in any way, return this one instance. It means "When Mercedes is requested from the ioc container, return this one instance".

This is also how Autofac does it: https://dotnetfiddle.net/taPUZZ and https://dotnetfiddle.net/hPVA8e.

[FaustoNascimento]

Could I suggest introducing new API to make it behave as discussed? It would just be an addition to the existing IoC without changing existing behaviour.

[canton7]

Can you find examples of how other IoC containers handle this? It would be good to get some inspriation for how they avoid making it confusing.