RFR: 8015315: Stream.concat methods

[Remi Forax]

On 07/01/2013 01:36 PM, Peter Levart wrote:
>
> On 07/01/2013 11:52 AM, Remi Forax wrote:
>> On 06/29/2013 02:58 AM, Henry Jen wrote:
>>> Hi,
>>>
>>> Please review the webrev that add concat static method to Stream and
>>> primitive Streams.
>>>
>>> http://cr.openjdk.java.net/~henryjen/ccc/8015315.0/webrev/
>>>
>>> Cheers,
>>> Henry
>>
>> Hi Henry,
>> I find the the cast to Spliterator<T> in Streams.concat() dubious,
>> I can not see how it can be correct, could you explain why this cast 
>> is Ok.
>>
>> cheers,
>> Rémi
>>
>
> Hi,

Hi,

>
> I think that if we want to concat say Stream<Integer> with 
> Stream<Long>, producing Stream<Number>, there would have to be an 
> unsafe cast somewhere. Since Stream<T> API apears to be covariant 
> (like for example Iterator<T>), casting Stream<? extends T> to 
> Stream<T> seems to be safe.

if Stream is covariant, it should be possible to create a Stream<T> from 
a Spliterator<? extends T>,
so there is no need of such unsafe cast.

>
> Regards, Peter
>

cheers,
Rémi