Thank you again for your answers. I think I just had a little idea,
(extremely) based upon Dhanji's answer.
As I said, I'm working with interfaces. So let's call them IntA and IntB
(A and B are still concrete classes and implement IntA and IntB
respectively):
@Provides IntA createIntA() {
A a = new A();
IntB b = new B(a);
a.setB(b); // method not defined in IntA, but well in A.
return a;
}
This suits me very fine since I don't have to change my interfaces, only
adding a set, and I avoid using the (heavy) AssistedInject.
Thank you,
Olivier
dg a écrit :
> also consider simply
>
> class A {
> @Inject A( B b ) {
> b.setA( this );
> }
> }
>
> Unless you really need to pass A to B's constructor.
>
> -d
>
>
> On Apr 17, 5:51 pm, "Dhanji R. Prasanna" <[email protected]> wrote:
>> Yea I was afraid of that. Well you could resort to setter injection and
>> write a @Provides method:
>> @Provides A get() {
>> A a = new A();
>> B b = new B(a);
>> a.setB(b);
>> return a;
>>
>> }
>>
>> Dhanji.
>>
>> 2009/4/18 Olivier Grégoire <[email protected]>
>>
>>> Thank you for that answer, however I may not use them as singletons, since
>>> they logically are not (well, I must keep track of several A's).
>>> I tried to simplify the problem and removed all interfaces (because I
>>> thought they weren't useful in the problem presentation), but basically, I'm
>>> indeed managing interfaces, and not concrete classes, and therefore a proxy
>>> suits very fine. The "identity equality" comment was not to show that I
>>> require it, it meant more that I want to speak about a logically same
>>> instance, not two different instances created by Guice.
>>> Is the behaviour that you describe applicable to other instances than
>>> singletons, even with some additional code (without having to create the
>>> proxy myself though)?
>>> Any other suggestion? If no, I'll keep on going with the AssistedInject.
>>> Olivier
>>> 2009/4/17 Dhanji R. Prasanna <[email protected]>
>>> It looks like you are talking about a circular relationship. If you mark
>>>> both as singletons and hide the dependency behind an interface, Guice will
>>>> automatically generate a proxy to hook this up for you.
>>>> You won't get identity equality (one will be a proxy), but the circular
>>>> relationship (1:1) will be maintained in effect.
>>>> Dhanji.
>>>> On Sat, Apr 18, 2009 at 12:25 AM, Olivier <[email protected]> wrote:
>>>>> Hello,
>>>>> I would like to create a 1 to 1 relationship between two components.
>>>>> Here is the "old-fashion" code that represent what I want to have.
>>>>> import static org.junit.Assert.*;
>>>>> import org.junit.Test;
>>>>> public class OneToOneRelationshipTest {
>>>>> static class A {
>>>>> final B b;
>>>>> A () { this.b = new B(this); }
>>>>> }
>>>>> static class B {
>>>>> final A a;
>>>>> B (A a) { this.a = a; }
>>>>> }
>>>>> @Test public void testOneToOneDependency() {
>>>>> A a = new A();
>>>>> assertEquals(a, a.b.a); // check identity
>>>>> }
>>>>> }
>>>>> I've thought about using AssistedInject to transfer a factory of B to
>>>>> A:
>>>>> import static org.junit.Assert.*;
>>>>> import org.junit.Test;
>>>>> import com.google.inject.*;
>>>>> import com.google.inject.assistedinject.*;
>>>>> public class OneToOneRelationshipWithGuiceTest {
>>>>> static interface Factory { public B create(A a); }
>>>>> static class A {
>>>>> final B b;
>>>>> @Inject A (Factory f) { this.b = f.create(this); }
>>>>> }
>>>>> static class B {
>>>>> final A a;
>>>>> @Inject B (@Assisted A a) { this.a = a; }
>>>>> }
>>>>> static class Module extends AbstractModule {
>>>>> public void configure() {
>>>>> bind(A.class);
>>>>> bind(Factory.class).toProvider(FactoryProvider.newFactory
>>>>> (Factory.class, B.class));
>>>>> }
>>>>> }
>>>>> @Test public void testOneToOneDependency() {
>>>>> A a = Guice.createInjector(new
>>>>> Module()).getInstance(A.class);
>>>>> assertEquals(a, a.b.a); // check identity
>>>>> }
>>>>> }
>>>>> However I'm wondering whether this is "too much" or not because my
>>>>> expectations are quite simple, but I feel like a more simple @Provides
>>>>> can help me. I just don't know how I could correctly modelize it,
>>>>> because I didn't see an example on the wiki.
>>>>> Can anyone help me getting rid of AssistedInject if possible?
>>>>> Olivier
> >
>
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