[webbeans-dev] Re: CreationalContext

[Scott Ferguson]

On Jan 9, 2009, at 2:49 AM, Gavin King wrote:

> Hrm, after further thought I'm not sure this is necessary.
>
> * for objects with normal scope types, you can just inject proxies, no
> need to recurse
> * dependent objects are unshared, so they don't get added to  
> CreationalContext
>
> So what cases, precisely, were you having problems with, Scott?

Even the most trivial case requires the capability:

@ApplicationScoped
class Foo {
   @Current Bar _bar;
}

@ApplicationScoped
class Bar {
   @Current Foo _bar;
}

Requiring proxies for all beans is a performance hit which is entirely  
unnecessary with the proper SPI.

If the tradeoff is a performance hit on every method call (proxy) for  
every bean, vs a slight added complexity in the _SPI_, i.e. an  
interface that 98% of developers _never even see_, it should be  
obvious that the SPI change is the right one.

> I guess I can that it might be useful for pseudo-scopes other than
> @Dependent, or possibly as a performance optimization...

It's not an "optimization", it's the basic overhead of the basic  
method call.

-- Scott
>
>
> On Fri, Jan 9, 2009 at 5:03 AM, Gavin King <gavin at hibernate.org>  
> wrote:
>> Folks, I would like to go ahead and write up this change, unless  
>> anyone objects.
>>
>> It's a hole that needs fixing.
>>
>> On Fri, Jan 2, 2009 at 4:19 PM, Gavin King <gavin at hibernate.org>  
>> wrote:
>>
>>> The alternate solution is something like:
>>>
>>>  interface CreationalContext {
>>>      <X> void add(Bean<X> bean, X instance); //registers an  
>>> "incomplete" instance
>>>  }
>>>
>>>  interface Contextual<T> {
>>>      public abstract T create(CreationalContext ctx);
>>>      ...
>>>  }
>>>
>>>  interface Context {
>>>      public <T> T get(Contextual<T> bean); //get any existing  
>>> instance
>>>      public <T> T get(Contextual<T> bean, CreationalContext ctx);
>>>                                                                     //get 
>>>  or create an instance
>>>
>>>      public Class<? extends Annotation> getScopeType();
>>>      boolean isActive();
>>>  }
>>>
>>>  interface Manager {
>>>      Object getInstanceToInject(CreationalContext ctx,
>>>                            InjectionPoint ij, Type type,  
>>> Annotation... bindings);
>>>      ...
>>>  }
>>>
>>> And getInstanceToInject() would be smart enough to return any object
>>> that had already been registered with the CreationalContext.
>>>
>>> Note that this solution addresses the problem of circular  
>>> references,
>>> and also fixes a hole in how the Manager knows about the  
>>> InjectionPoint.
>>
>>
>> --
>> Gavin King
>> gavin.king at gmail.com
>> http://in.relation.to/Bloggers/Gavin
>> http://hibernate.org
>> http://seamframework.org
>>
>
>
>
> -- 
> Gavin King
> gavin.king at gmail.com
> http://in.relation.to/Bloggers/Gavin
> http://hibernate.org
> http://seamframework.org
>
>