hg: lambda/lambda/jdk: initial small set of extension methods on Collection and List which provide functional-style variants of common operations.

[Howard Lovatt]

I would suggest putting them as an inner class within the interface, e.g.:

public interface Collection ... {
   boolean retainAll( Predicate<? super E> filter ) default Trait.retainAll;
   ...
   static final class Trait {
     private Trait() {}
     public static boolean retainAll( final Collection self, final
Predicate<? super E> filter ) { ... }
     ...
  }
}

That way everything is in one place, including the JavaDoc.

On 19 August 2011 17:26, Neal Gafter <neal at gafter.com> wrote:

> On Thu, Aug 18, 2011 at 3:47 PM, Mike Duigou <mike.duigou at oracle.com>
> wrote:
>
> > > Hi Paul, the real name of these classes is garbage class.
> > > But ListGarbage is not that cool :)
> > >
> > > As Mike says, it's just the first cut, I really hope we will not
> > > have any of these classes at all at the end.
> >
> > Where do you advocate that they should go? For the collection extensions
> > the obvious location is Collections. Should we just create parallel
> classes
> > for List, Set, Map, etc? ie. Lists, Sets, Maps, etc.
> >
>
> They should go in the interface.  For example:
>
> public interface Collection ... {
>    ...
>
>    /**
>    * Retains all of the elements of this collection which match the
> provided
>    * predicate.
>    *
>    * @param filter a predicate which returns {@code true} for elements to
> be
>    * retained.
>    * @return {@code true} if any elements were retained.
>    */
>    // XXX potential source incompatibility with retainAll(null) now being
> ambiguous
>    boolean retainAll(Predicate<? super E> filter) {
>        boolean retained = false;
>        Iterator<E> each = this.iterator();
>        while(each.hasNext()) {
>            if(!filter.eval(each.next())) {
>                each.remove();
>            } else {
>                retained = true;
>            }
>       }
>
>        return retained;
>    }
>
> ...
> }
>
>


-- 
  -- Howard.