Custom stream extensions

Brian Goetz brian.goetz at
Sun Feb 3 14:18:07 PST 2013

Right.  During initial development, all these classes were public, 
mostly for convenience of testing.

There always has been an extensibility strategy in place, but it will 
sadly not be ready for 8.  Eventually, we will make public the XxxOp 
classes, which will enable you to write your own ops, and thread them 
into pipeline with the pipeline() method:


The built-in ops all use this API, so we have been eating our own 
dogfood.  However, it is clear that this API is not yet ready to be 
carved in stone.  So the responsible thing to do is to keep it private 
for now, until it is ready, at which point this extensibility mechanism 
will be available to everyone.

On 2/3/2013 4:56 PM, Arul Dhesiaseelan wrote:
> I was able to add extensions to my custom list implementation in earlier
> builds.
>    public MyStream<E> stream() {
>      return new MyReferencePipeline<>(() -> Arrays.spliterator((E[])
> this.toArray(), 0, this.size()), StreamOpFlag.IS_SIZED |
> StreamOpFlag.IS_ORDERED);
>    }
> Now that, ReferencePipeline is made package local, this approach is no
> longer possible.
> It was extremely useful to extend some of these core classes outside the
> package and toss in extensions with minimal coding. I assume this is not
> encouraged?
> Thanks,
> Arul

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