I have come up with a solution that allows me to find all of the Singleton
bindings in the module using the bind(...).in(Singleton.class) using the
SPI mechanisms for introspecting a *Module* and not an *Injector*.
To modify my previous example code:
AbstractModule mod = new AbstractModule() {
@Override
protected void configure() {
bind(Vehicle.class).to(Car.class).in(Singleton.class);
}
};
Elements.getElements(mod).forEach((e) -> {
e.acceptVisitor(new DefaultElementVisitor<Void>() {
public <T> Void visit(Binding<T> binding) {
if (Scopes.isSingleton(binding)) {
System.out.println(binding.getKey() + " is singleton = " +
Scopes.isSingleton(binding));
}
return null;
}
});
});
This correctly observes that the binding of Vehicle is a singleton:
Key[type=com.instinet.gtr.cucumber.caas.di.TestGuice$Vehicle,
annotation=[none]] is singleton = true
On Wednesday, 4 November 2015 09:13:02 UTC, jwa wrote:
>
> Thomas - Having re-read your response I understand what you are alluding
> to; the two-liner you are suggesting makes the Car a singleton within the
> Injector. I can confirm that if I change the binding to your suggested
> two-liner it does indeed note the provisioned Car is a singleton, i.e.
>
> bind(Vehicle.class).to(Car.class);
> bind(Car.class).in(Singleton.class);
>
> Will output:
>
> Key[type=com.instinet.gtr.cucumber.caas.di.TestGuice$Car,
> annotation=[none]] is singleton = true
>
>
> However, that is not functionally equivalent to my previous module
> configuration. I am happy for multiple Cars to exist in the system, I
> simply want every instance of Car that is injected to fulfill Vehicle to
> use the same instance.
>
> ---
>
> Using the TypeListener and ProvisionListener SPI mechanisms I am unable to
> observe any information about Vehicle, I am only notified about the type
> Car. Therefore, it seems impossible to observe the fact that the binding of
> Vehicle is within Singleton scope?
>
> @opn - A valid point, I hadn't considered the syntactic sugar I could
> offer with my own domain-specific abstract module. That's an idea which is
> useful in numerous places.
>
> Thanks Again.
>
>
>
>
>
>
>
> On Wednesday, 4 November 2015 08:05:55 UTC, opn wrote:
>>
>> Also, the modules I'm consuming are provided by application developers
>> who use my framework. I've published in the API they need to produce Guice
>> modules. I'm not willing to be more restrictive and tell them to use
>> specific syntax, that would reflect poorly on my framework.
>>
>> You could provide an abstract Guice module to hide the tedious binding
>> procedure from developers using your framework. See for example:
>>
>>
>> https://github.com/ArcBees/GWTP/blob/master/gwtp-core/gwtp-mvp-client/src/main/java/com/gwtplatform/mvp/client/gin/AbstractPresenterModule.java#L49
>>
>> On 11/04/2015 12:11 AM, Jamie Astin wrote:
>>
>> Hi Thomas,
>>
>> Thanks for taking the time to reply. The output posted is the total
>> output from my test.
>>
>> Therefore, Guice is only observing one provision. Thus, its not like
>> theres a second provision I could inspect.
>>
>> Also, the modules I'm consuming are provided by application developers
>> who use my framework. I've published in the API they need to produce Guice
>> modules. I'm not willing to be more restrictive and tell them to use
>> specific syntax, that would reflect poorly on my framework.
>>
>> If the two separate bindings do work, this surely suggests a Guice bug?
>> As far as I can tell your two-liner should be functionally equivalent to my
>> on-liner?
>>
>> I'll try the two-liner tomorrow. My intention would be to debug + raise a
>> bug / pull request if it actually fixes the underlying problem... Unless
>> someone can explain the disparity between the one/two-liner?
>>
>> Thanks again!
>>
>>
>> On Nov 3, 2015 21:17, "Thomas Broyer" <[email protected]> wrote:
>>
>>> The Car binding isn't a Singleton; the Vehicle one is. Using separate
>>> bind() calls might do what you want:
>>>
>>>
>>>
>>> bind(Vehicle.class).to(Car.class);
>>>
>>> bind(Car.class).in(Singleton.class);
>>>
>>>
>>>
>>> (I don't know listeners much so can't really help beyond the above)
>>>
>>>
>>>
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