I thought today's meeting was pretty good. Based on one of the discussion points, I wanted to try putting together an interface that described the boot paradigm. Unfortunately even in Java 8 it doesn't work too well, I cannot assign a static variable in an interface the way I can in an abstract class. More importantly, it doesn't give us the private level expectation I would look for in this case. I best I could come up with using an interface is:Why BeanManager? I think it would be better to return CDI or its subclass rather than this low-level SPI. With the CDI class we get more user-friendly Instance<T> for free. We could also expose Event<T> similarly.
public interface CDIBooter {default BeanManager initialize() {return initialize(new HashMap<>());}
BeanManager initialize(Map<?,?> properties);
void shutdown();
class BootHolder {
static CDIBooter instance = null;
}
static CDIBooter instance() {if(BootHolder.instance == null) {ServiceLoader<CDIBooter> serviceLoader = ServiceLoader.load(CDIBooter.class);for(CDIBooter booter : serviceLoader) {BootHolder.instance = booter;break;}}return BootHolder.instance;}}
where as the abstract class is a bit briefer, while also being private.
public abstract class CDIBooter {public BeanManager initialize() {return initialize(new HashMap<>());}
public abstract BeanManager initialize(Map<?,?> properties);
public abstract void shutdown();
private static CDIBooter instance = null;public static CDIBooter instance() {if(instance == null) {ServiceLoader<CDIBooter> serviceLoader = ServiceLoader.load(CDIBooter.class);for(CDIBooter booter : serviceLoader) {instance = booter;break;}}return instance;}}
Obviously ignore concurrency issues, etc. It does look to be safer to do an abstract class, rather than a factory-interface.
John
On Wed Dec 17 2014 at 10:40:44 AM Antoine Sabot-Durand <antoine@sabot-durand.net> wrote:
Hi all,_______________________________________________
I have business matter and will have to shorten the meeting tonight (half an hour instead of 1h).
I updated the SE doc and Antonio added useful annexes : https://docs.google.com/document/d/1LgsGT-AAlrF72Z5pW4xNQiVjUHGUME46ZmB-wwF35Yw/edit?usp=sharing
I propose we focus on this in these 30 mn
regards,
Antoine
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