Well, I was trying to make the example simple, but I think this makes
sense. I've been looking at the child injector thing, but I was unaware
that you could inject an Injector like that (am I right in assuming that'll
be the same Injector that creates the ClientFactory?). I think that might
be exactly what I need. Thanks!
On Thursday, 2 October 2014 13:05:00 UTC-5, Nate Bauernfeind wrote:
>
> Ok, I see. I've found most of my uses cases of assisted injection are
> summed up here:
>
> 1. You have single class that you want to create and manage multiple
> instances. This class also uses objects that are already part of your guice
> object graph (shared services, etc). I prefer assisted injection for these.
>
> class Foo {
> @Inject
> public Foo(FooService fooService, @Assisted String name) { ... }
> public static interface Factory {
> Foo createFoo(String name);
> }
> }
>
> public class FooManager {
> private final Foo.Factory _fooFactory;
> @Inject
> public FooManager(Foo.Factory factory) {
> _fooFactory = factory;
> }
> public Foo onFooSubscribed(String subscriptionName) {
> Foo foo = _fooFactory.create(subscriptionName);
> // TODO: save foo for later.
> return foo;
> }
> }
>
> 2. You have many classes that you want to create and manage as a group,
> and you want to create multiple groups. Many of these classes will use
> objects that are already part of your guice object graph. I prefer using
> childInjectors for these and create my own factory (which seems similar to
> assisted inject). Usually you'll want the one object you pull out of this
> graph be able to start and stop the entire sub-graph (so that you can clean
> up when it's time for that object graph to disappear).
>
> public class ClientFactory {
> private final Injector _injector;
>
> @Inject
> public ClientFactory(Injector injector) {
> _injector = injector;
> }
>
> public Client create(ClientConfiguration config) {
> return _injector.createChildInjector(new
> ClientModule(config)).getInstance(Client.class);
> }
>
> private static class ClientModule extends AbstractModule {
> ...
> }
> }
>
> public class ClientManager {
> private final ClientFactory _clientFactory;
> @Inject
> public ClientManager(ClientFactory factory) {
> _clientFactory = factory;
> }
> public Client onClientSubscribed(ClientConfiguration clientConfig) {
> Client client = _clientFactory.create(clientConfig);
> client.start();
> // TODO: save client for later.
> return client;
> }
> }
>
> 3. If you have a simple object like Bar here, then I wouldn't bother
> using Guice for it at all as there is no gain (unless, of course!, you've
> got some injection listener that MUST be aware of instances of Bar).
> class Bar {
>
> public Bar(String name) { ... }
> }
>
> public class BarManager {
> public Bar onBarSubscribed(String barName) {
> Bar bar = new Bar(barName);
> // TODO: save bar for later.
> return bar;
> }
> }
>
>
> From your example, I can't tell if you actually are trying to figure out
> how to inject many instances of Bar or if you're just trying to be simple
> for the sake of the email thread. So, if this is not helpful at all, please
> say so and I'll try again.
>
> Nate
>
>
>
>
>
>
> On Thu, Oct 2, 2014 at 12:58 PM, Brad Micholson <[email protected]
> <javascript:>> wrote:
>
>> Actually, that doesn't make any sense at all. Forgive me, I've never used
>> AssistedInject before. I wouldn't want to annotate someParameter at all;
>> that's what I want to explicitly pass in...
>> I guess the issue is that Example doesn't have an @Inject annotation, so
>> I can't really use AssistedInject on it.
>>
>>
>>
>> On Thursday, 2 October 2014 10:31:17 UTC-5, Brad Micholson wrote:
>>>
>>> public class Example implements ExampleInterface {
>>> private final int moduleId;
>>> public Example(int moduleId){
>>> this.moduleId = moduleId;
>>> }
>>> }
>>>
>>> In my Guice module, I do
>>>
>>> @Provides @Module1
>>> private ExampleInterface provideModule1Example(@Module1 int moduleId){
>>> return new Example(moduleId);
>>> }
>>>
>>> @Provides @Module2
>>> private ExampleInterface provideModule2Example(@Module2 int moduleId){
>>> return new Example(moduleId);
>>> }
>>>
>>> So, injecting an ExampleInterface, annotated with either @Module1 or
>>> @Module2, uses the same implementation, just with a different parameter. If
>>> I want to add an AssistedInject parameter to the constructor, and create a
>>> factory for it, I'd have something like
>>>
>>> public interface ExampleInterfaceFactory {
>>> ExampleInterface create(Object someParameter);
>>> }
>>>
>>> I'd want to annotate someParameter, but the annotation would depend on
>>> how the ExampleInterface is annotated where it's injected.
>>>
>>> I hope that all makes sense. I'm still fairly new to Guice...
>>>
>>>
>>>
>>> On Wednesday, 1 October 2014 19:42:58 UTC-5, Nate Bauernfeind wrote:
>>>>
>>>> Can you explain what you mean with a small amount of code? Can you
>>>> annotate the assisted inject factories? Maybe you can mix PrivateModule's
>>>> along with AssistedInject factories to get the effect you're looking for
>>>> (and potentially exposing the factory with an annotation?).
>>>>
>>>> Nate
>>>>
>>>> On Wed, Oct 1, 2014 at 6:38 PM, Brad Micholson <[email protected]>
>>>> wrote:
>>>>
>>>>> I'm wondering if there's a better way to do this than I'm currently
>>>>> doing...
>>>>>
>>>>> I want to, essentially, bind multiple configurations of a class, based
>>>>> on an annotation. I don't want a separate class binding for different
>>>>> annotations; I just want different parameters in the constructor. Right
>>>>> now, I'm creating multiple providers, which contain differently annotated
>>>>> parameters.
>>>>> However, I'd love to be able to use AssistedInject, as I find I'm
>>>>> creating a ton of factory classes. There doesn't really seem to be a way
>>>>> to
>>>>> do that. I'd initially thought I could maybe create multiple abstract
>>>>> implementations of the factory, and annotate the parameters, but it seems
>>>>> the factory must be an interface...
>>>>>
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>>>>>
>>>>
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>
>
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