If you mean the ConfigurationBilderFactory - proposed by me - I have to admit that when I read the static thing I realized how stupid I was. The main thing I wanted it for (the constructor thing) can be done with the static methods (maybe it's a bit less convinient).
On Wed, 01 Oct 2003 15:05:53 +0200, Johan Lindquist <[EMAIL PROTECTED]> wrote:
Wouldn't the configuration passed to the factory will make sure the service is returned in a 'usable' state? The user doesn't do any configuration at that level?
And the service interface shouldn't really allow configuration changes or?
And I am all for the pattern to ensure consistency in created objects ... Not sure if it applies here though ...
Johan
On Wed, 01 Oct 2003 15:05:16 +0200, Christian Essl <[EMAIL PROTECTED]> wrote:
You are right HiveMind always returns the same instance, but I mean there can be services which have no state or the state of which is just defined at construction time and for these it makes in my opinion sense to declare them as (default-variant) static fields. Further for those Services the static field gives a level of indirection.
But certainly the more intresting idea was the one of static-factory- methods. I personally hate nothing more than making a default constructor for classes which need external data to be ready for usage. I don't want to construct my classes and than rely on the user that he might set the needed data sometime . When a class is constructed it should be in a valid state or otherwise throw an Exception. And as you know a pattern to ensure that is to use a static-factory-method and a private (maybe protected) constructor.
On Wed, 01 Oct 2003 14:29:49 +0200, Johan Lindquist <[EMAIL PROTECTED]> wrote:
I may have misunderstood this - but doesn't hivemind always return the same instance when you ask for a service once it has created one (unless it is a threaded service model, when you are worried about state anyway and probably want different instances)? If so, what is the need to have a static instance? I suppose I can see a use for it to share data between threads, but the singleton service should suffice?
Johan
On Wed, 01 Oct 2003 13:52:58 +0200, Christian Essl <[EMAIL PROTECTED]> wrote:
That's very good (and fast implemented). But do you realy have to do the double-check on the class. I mean the user sees anyway what class it is from the JavaDoc and HiveMind will always check that it fits the Service interface.
Sure if the static field changes this ensures consistency, but on the other hand it would be also very convient to change all services referenced but just changing the static field without the need to go into the module.
On Wed, 1 Oct 2003 12:40:12 +0200, Knut Wannheden <[EMAIL PROTECTED]> wrote:
I have created a copy of the hivemind.BuilderFactory service which allows me
to write:
<invoke-factory service-id="my.BuilderFactory"> <construct class="foo.Bar" static-field="foo.Bar.INSTANCE"/> </invoke-factory>
given that I have something like:
package foo; public interface Bar { static final INSTANCE = new BarImpl(); }
The class attribute is used to check that the object specified by the
static-field is of a given type, which is an interface in this example.
--knut
That's certainly a good idea.objects
On Wed, 1 Oct 2003 07:50:42 +0200, Knut Wannheden <[EMAIL PROTECTED]> wrote:
> Hi,
>
> I was wondering whether it would make sense to extend the BuildFactory
> service (or maybe add a new wervice) to also be able to construct> by
> returning the value of a classes static field or by calling a static
> method
> on a class. The former would obviously be simpler. E.g. (as a new
> service):
>
> <invoke-factory service-id="hivemind.StaticBuilderFactory">
> <construct class="foo.Bar" static-field="BAZ">
> <set.../>
> </construct>
> </invoke-factory>
>
> --knut
>
>
>
>
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