Stream is AutoCloseable, Stream.onClose

Remi Forax forax at
Fri Jun 21 10:28:03 PDT 2013

onClose takes a callback and not the resource,
is valid in my opinion but not


On 06/21/2013 07:19 PM, Joe Bowbeer wrote:
> Your explanation makes little sense to me. I've never seen onEvent 
> methods used in a fluent style, except perhaps in a builder pattern, 
> and even then the names are usually clearer, for example, 
> registerOnCloseHandler.
> The extent to which our objection is overblown is hard to gauge but I 
> think plenty of better alternatives exist.
> Joe
> On Jun 21, 2013 9:26 AM, "Brian Goetz" <brian.goetz at 
> <mailto:brian.goetz at>> wrote:
>         I like the benefits, though I think the onClose name is confusing.
>         In many frameworks, the onError/onExit/onEvent naming style is
>         reserved
>         for method names in callback interfaces.  It is the prevalent
>         convention
>         currently.  So I'd expect onClose() to be the method that is
>         called-back
>         upon closing.
>     After reflection, I think this concern, while valid, may be overblown.
>     In a functional system, it is totally natural to treat "onXxx(f)"
>     as "run function f on Xxx".  For example:
>       new Window()
>         .onClose(closeFn)
>         .onMinimize(minimizeFn)
>         .onClick(clickFn);
>     I think if someone saw this code, they would not be confused at
>     all; its very clear what is going on.
>     In a purely functional system, all the onXxx would take a
>     function.  In a purely OO system, all the onXxx would be methods
>     that get called at the appropriate time.  Confusion would come
>     only if we mixed the two "too much".  Its not obvious what the
>     granularity at which it becomes too much, but "within the same
>     abstraction" might be a reasonable place to draw that line.
>     If there were an alternative that didn't completely suck, I'd be
>     open to that.  (So far, though, no such alternative has emerged.)

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