ADBA Add type safe newFactory method

[Frédéric Montariol]

I really like the alternative newFactory static method taking a Class
parameter :
public static <T extends DataSourceFactory> T newFactory(Class<T> clazz)
It would allow elegant Kotlin reified generic type extension function !

But there is something I don't like, this is the fact that
DataSourceFactory.newFactory
returns null if no corresponding class is found, causing NPE on next method
call : factory.builder()
I would prefer if it throws an Exception.

Le ven. 13 juil. 2018 à 19:48, Douglas Surber <douglas.surber at oracle.com> a
écrit :

> The internal consensus is to change the spec exactly as you suggest and
> require the explicit cast if that’s what the user wants. I still would like
> to hear what others think.
>
>   public static DataSourceFactory newFactory(String name) { … }
>
>   DataSourceFactory factory =
> DataSourceFactory.newFactory(“my.adba.MyFactory”);
>
> or
>
>   MyFactory factory = (MyFactory)
> DataSourceFactory.newFactory(“my.adba.MyFactory”);
>
> Douglas
>
>
>
> > On Jul 13, 2018, at 9:46 AM, Douglas Surber <douglas.surber at oracle.com>
> wrote:
> >
> > This is a good question. I defined it the way I did specifically to
> avoid the explicit cast. I have no strong opinion on which is better. I’ll
> ask for opinions internally and I hope other members of this list give
> their thoughts.
> >
> > Douglas
> >
> >> On Jul 13, 2018, at 8:26 AM, Mark Rotteveel <mark at lawinegevaar.nl>
> wrote:
> >>
> >> The existing DataSourceFactory.newFactory(String name) has an unchecked
> cast using a (possibly inferred) type parameter.
> >>
> >> Would it make sense to add an alternative with the signature:
> >>
> >> public static <T extends DataSourceFactory> T newFactory(Class<T> clazz)
> >>
> >> When you use this, you are tied to an ADBA implementation at compile
> time, but it will make this more type-safe.
> >>
> >> And maybe the unchecked cast (and type parameter) should be removed
> from the variant taking a name only.
> >>
> >> That is, change the method to
> >>
> >> public static DataSourceFactory newFactory(String name) {
> >>   if (name == null) throw new
> IllegalArgumentException("DataSourceFactory name is null");
> >>   return ServiceLoader
> >>           .load(DataSourceFactory.class)
> >>           .stream()
> >>           .filter(p -> p.type().getName().equals(name))
> >>           .findFirst()
> >>           .map(Provider::get)
> >>           .orElse(null);
> >> }
> >>
> >> Any casts would then be the explicit responsibility of the developer,
> instead of accidental due to type inference.
> >>
> >> Mark
> >> --
> >> Mark Rotteveel
> >
>
>