Re: new instance required when using InstancePerLifetimeScope not under a lifetime scope

[Travis Illig]

It returns the same instance because you're resolving the instance from the container. A container is an implicit lifetime scope.

If you want different instances IN different lifetime scopes, you have to start a new lifetime scope.

var builder = new ContainerBuilder();

builder.RegisterType<MyType>().InstancePerLifetimeScope();

var container = builder.Build();

using(var scope = container.BeginLifetimeScope())

{

  // Resolve from a SCOPE not the CONTAINER

  var obj = scope.Resolve<MyType>();

}

If you want a different object every time you ask for one, you can specify InstancePerDependency() or just leave off the lifetime specifier entirely.

builder.RegisterType<MyType>();

// same as

builder.RegisterType<MyType>().InstancePerDependency();

Then when you resolve, you get a new one every time, regardless of the scope.

-T

On Wednesday, January 30, 2013 2:50:40 PM UTC-8, wallac...@gmail.com wrote:

I'm migrating some things to InstancePerLifetimeScope, this is working great for things that I can migrate.

However consider this example:

Resolve returns the same object for service1 and service2. 

Is there an option to return different objects when NOT under a lifetime scope?

Cheers and regards

Wallace

[Travis Illig]

In a one-liner? No, that's not supported out-of-the-box. You've sort of asked for conflicting lifetime definitions for the same component. Knowing that the container is a lifetime scope, the requirement effectively reads:

• In one lifetime scope I want the same instance returned but
• In another lifetime scope I want new instances every time.

What you can potentially do is override the service registration at the time you create your child lifetime scope, like this:

var builder = new ContainerBuilder();

builder.RegisterType<MyDependency>();

var container = builder.Build();

// Out here, every time you ask for a new MyDependency

// you'll get a new instance.

using(var scope =

  container.BeginLifetimeScope(

    b => b.RegisterType<MyDependency>().InstancePerLifetimeScope()))

{

  // In here, you'll get the same one every time

  // and it won't be one that you've gotten outside

  // the scope.

}

So, technically it's possible, it's just not free.

-T

On Wednesday, January 30, 2013 3:26:29 PM UTC-8, wallac...@gmail.com wrote:

Travis, 

>It returns the same instance because you're resolving the instance from the container. A container is an implicit lifetime scope.

I'm familiar with how this works when using BeginLifetimeScope.

My question relates to when resolving the dependency when NOT under a lifetime scope. You've answered this by saying 'a container is an implicit lifetime scope' but I'm asking for a way around this:

That is, is it possible to have:

1) when T resolved under  BeginLifetimeScope autofac will return the SAME instance

2) when T resolved NOT under BeginLifetimeScope autofac will return a NEW instance.

?

[Travis Illig]

What I mean is that there's no "out of the box automatic support" for it. You have to write additional code like this to make it happen.

On Wednesday, January 30, 2013 4:31:12 PM UTC-8, wallac...@gmail.com wrote:

thats really cool, thanks!

and just to clarify when you say 'its just not free' <-- you are referring to the overhead of the ContainerBuilder on this line:

>using (var scope = container.BeginLifetimeScope(b => b.RegisterType<DateTimeService>().InstancePerLifetimeScope()))

?