Re: [infinispan-dev] Generics usage in org.infinispan.util.ClassFinder
On 7 oct. 09, at 12:21, Galder Zamarreno wrote:
On 10/07/2009 12:11 PM, Emmanuel Bernard wrote:
> Class<?> is the closest equivalent to Class. It adds no burden at
> all
> (people can still use the raw type if they wish to stay in the pre-5
> era). And literally Class<?> means what you've described: "we
can't
> say anything about the Class type returned"
I think it's a burden cos you're forcing client to either accept
Class<?> or cast to Class. Example:
A method defined as:
public static List<Class<?>> infinispanClasses();
Any client needs to do:
List<Class<?>> ispnClasses = ClassFinder.infinispanClasses(cp);
A client can't do:
List<Class> ispnClasses = ClassFinder.infinispanClasses(cp);
I see that as a burden on the client cos you're forcing the client to
deal with generics that say nothing.
Ah so you like generics and their type-safety and you don't in the
same declaration :)
Generally speaking Type and Type<?> are different. Type is more
equivalent to Type<? extends Object> I think. This is particularly
true of collections where you cannot add anything but null in a
Collection<?> while you can add anything in Collection. In the case of
Class<T>, there is no consumer method taking T, so the difference is
not visible AFAIK.
That being said, List<Class> is a PITA for people using generics
property as you can't cast to List<Class<?>>. You basically have to
copy the list over.