Proposal: Automatic Resource Management

[Neal Gafter]

I think you're missing the point, Josh.  People do this today with
Closeable, because that's the closest interface available that could
be used to perform this function, but clients suffer from its
exception signature.  Disposable is better in one way - it would be
retrofitted onto more classes - but much worse in its exception
signature.  You're saying that there's no pain because you can't use
it as a parameter type.  I'm saying that is the cause of the pain.
The language construct that you're proposing does not supplant this
technique of resource management, but the APIs you're proposing to go
with it interfere with the technique.

On Tue, Mar 3, 2009 at 7:41 PM, Joshua Bloch <jjb at google.com> wrote:
> Neal,
> I think you may be missing the point here.  The only use of this interface
> would be to make a type eligible for automatic resource management.  It
> would never be used as a parameter type.  There'd be no pain at all
> associated with it.
>           Josh
>
> On Tue, Mar 3, 2009 at 6:47 PM, Neal Gafter <neal at gafter.com> wrote:
>>
>> I guess I assumed you were aware why people complain about
>> Closeable.close() throwing IOException.  Josh alluded to this when he
>> said that Disposable won't be terribly useful as a parameter type.
>> When you pass it somewhere, the receiver must assume that the close()
>> method throws any Exception, and that forces the receiver to write
>> code to handle the whole Exception hierarchy.  I think it's likely
>> that programmers would want to pass a Disposable around so that the
>> receiver can put a region of code under control of the resource (i.e.
>> dispose it when the receiver arrives at some particular point of
>> completion).  I'm afraid this would just be trading one set of pain
>> points for another.
>>
>> On Tue, Mar 3, 2009 at 6:26 PM, Reinier Zwitserloot
>> <reinier at zwitserloot.com> wrote:
>> - Show quoted text -
>> > The new Disposable idea makes this proposal much cleaner, Josh. I like
>> > it.
>> >
>> > Neal, could you perhaps elaborate on the pain that Disposable is going
>> > to cause? Insinuating that proposals are Bad Ideas without any
>> > specifics whatsoever seems better suited to some sort of voting cycle.
>> > On this mailing list it seems counter-productive to say the least.
>> >
>> >  --Reinier Zwitserloot
>> >
>> >
>> >
>> > On Mar 4, 2009, at 03:08, Neal Gafter wrote:
>> >
>> >> Given all the gnashing of teeth over the fact that Closeable's close
>> >> method throws IOException, I can only imagine the pain that
>> >> Disposable.close() throwing Exception will cause.
>> >>
>> >> On Tue, Mar 3, 2009 at 5:47 PM, Joshua Bloch <jjb at google.com> wrote:
>> >>> I have modified the proposal in light of Mark's example.  The only
>> >>> change is
>> >>> that the Disposable interface is no longer parameterized.  This
>> >>> eliminates
>> >>> the incompatibility noted by Neal; so far as I know, the revised
>> >>> proposal
>> >>> introduces no incompatibilities. It can be found here:
>> >>> http://docs.google.com/Doc?id=ddv8ts74_0vnstdfdh .
>> >>>     Happy reading,
>> >>>
>> >>>     Josh
>> >>>
>> >>>
>> >>
>> >
>> >
>> >
>>
>
>