Yet another run at reduce (collect)

[Aleksey Shipilev]

Thanks. Another question: it seems to me that collector passed into
collect(...) can actually be reused, since I would expect the library
will call makeResult() at least once to bootstrap the collector? Or, is
the library reusing the one passed via the parameter? I.e. instead of:

 stream().collect(new MyCollector()).getResult();

 class MyCollector implements Collector<Long, MyCollector> {
    public MyCollector makeResult() {
        return new MyCollector();
    }

    public void accumulate(MyCollector result, Long value) {
        result.result += value;
    }

    public MyCollector combine(MyCollector result, SumLongSink other) {
        result.result += other.result;
        return result;
    }

    public long getResult() {
        return result;
    }
 }

...can I do this?

 static final MyCollector MY_COLLECTOR = new MyCollector()
 (...)
 stream().collect(MY_COLLECTOR).getResult();


-Aleksey.

On 01/10/2013 01:13 AM, Brian Goetz wrote:
> The simple rule is:
>  - makeResult should return a new result container for every call
>  - combine may return one of its arguments, or a new result
> 
> 
> 
> On 1/9/2013 4:10 PM, Aleksey Shipilev wrote:
>> On 01/09/2013 11:25 PM, Doug Lea wrote:
>>> On 01/09/13 13:56, Brian Goetz wrote:
>>>> I've pushed a rename to collect().  Check it out.
>>>
>>> Yay! Thanks!
>>
>> Ok, this is quite an intrusive change to adapt for my performance tests.
>> Can you please add more Javadocs for Collector? In fact, I need more
>> details on:
>>   a) Should makeResult() return the new result on every call?
>>   b) Can combine(result, other) return updated $result, or it should
>> return distinct collectable?
>>
>> -Aleksey.
>>