hello, I think you can get what you need using a simple factory instead of a vanilla Provider:
interface DependentOnSpecialFactory {
DependentOnSpecial create(SpecialThing currentSpecialThing);
}
and then it sounds like you can simply use a FactoryProvider to bind this:
public class YourModule extends AbstractModule {
@Override
protected void configure() {
// ....whatever else you do
bind(DependentOnSpecialFactory.class)
.toProvider(FactoryProvider.newFactoryProvider(
DependentOnSpecialFactory.class, DependentOnSpecial.class)));
}
}
You could do a similar thing with Scopes, but for such tightly coupled
creation logic of:
1) identifying the current SpecialThing
2) effectively passing it to the Provider (in your model) to create an
instance of DependentOnSpecial
then I think a straightforward factory is clearer.
-Fred
On Thu, Jan 14, 2010 at 3:06 AM, Marcel <[email protected]> wrote:
> Hi, I'm new to Guice and I'm trying to convert an existing application
> to use guice. Most parts work quite fine, but for one problem I didn't
> find a nice solution so far.
>
> I created a little example that hopefully illustrates my problem. I
> have a class that depends on a list of SpecialThings and a provider
> that itself depends on the *currently active* SpecialThing, i.e., the
> provider needs to know what SpecialThing is active when calling get()
> because this affects its return value:
>
> @Inject
> public TestExample(final List<SpecialThing> specials, final
> Provider<DependentOnSpecial> provider)
> {
> this.specials = specials;
> this.provider = provider;
> }
>
>
>
> public void run()
> {
> for (final Special currentSpecial : specials)
> {
> final DependentOnSpecial dep = provider.get();
> // provider.setSepcialThing(special); // ???
> for (final String string : dep.elements())
> {
> System.out.println(string);
> }
> }
> }
>
> However, I think this is not the right way how to do it in Guice,
> right? I thought about using my own scope but I don't didn't
> understand how I can configure the scope with a particular instance of
> SpecialThing. SpecialThing is itself not free of dependencies, i.e.,
> it cannot be created using no-scope.
>
> Sorry, I got lost in my dependencies somehow :-}
>
> Summarized:
> I have a singleton List<SpecialThings>.
> I have Components that depend on the currently active, SpecialThing,
> i.e., the Injector should inject this active instance to the
> providers.
>
> It sounds like needing a scope but how can I achieve this notion of
> *active* SpecialThing from singleton list?
> Thanks in Advance.
>
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>
>
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