Nested dependencies with different lifetime scopes

[Jeremy Lew]

I have chased down bugs a few times which have resulted from component registered as SingleInstance that has a dependency registered as InstancePerLifetimeScope.  The solution, of course, was to change the outer component's registration to InstancePerLifetimeScope as well.  However I was wondering whether it would be reasonable for the container to refuse to inject a dependency whose lifetime scope if less than the component being injected?  I can't think of a scenario where I'd want this to succeed.

[Nicholas Blumhardt]

Hi Jeremy, admittedly they're rare, but valid cases do exist.

If you're able to, using InstancePerHttpRequest() or a similar specific sharing model (rather than IPLS(), which is very flexible) will turn up these kinds of bugs. If a singleton references an IPHR() component, Autofac will throw an (almost informative) exception.

Cheers,

Nick

On 3 November 2011 06:25, Jeremy Lew <jerem...@gmail.com> wrote:

I have chased down bugs a few times which have resulted from component registered as SingleInstance that has a dependency registered as InstancePerLifetimeScope.  The solution, of course, was to change the outer component's registration to InstancePerLifetimeScope as well.  However I was wondering whether it would be reasonable for the container to refuse to inject a dependency whose lifetime scope if less than the component being injected?  I can't think of a scenario where I'd want this to succeed.

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[Jeremy Lew]

Thanks, didn't know about InstancePerHttpRequest(). A related question:  If I do have the situation described above, and I declare the outer component's constructor using the factory pattern like this:

public MySingletonComponent(Func<MyInstancePerLifetimeScopeComponent>  factory)
{
  _factory = factory;
}

...at the point that I actually call the factory, will it obey the lifetime scope semantics for whatever lifetime scope happens to be in play?  (Hoping the answer is yes.)

Jeremy

[Jeremy Lew]

Actually, thinking about this more, I don't see how Func could possibly behave like that, it must be tied to the lifetime scope that injected the Func, right?

[Nicholas Blumhardt]

Not exactly sure what behaviour you mean - correct though, a Func is tied to and produces results in the lifetime scope that injected it.

On 4 November 2011 06:27, Jeremy Lew <jerem...@gmail.com> wrote:

Actually, thinking about this more, I don't see how Func could possibly behave like that, it must be tied to the lifetime scope that injected the Func, right?

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[Jeremy Lew]

Okay, thanks  I think Owned<> will solve my use-case this time.