I thought we were going to Java 7 for 2.0? Gary
-------- Original message -------- From: Damjan Jovanovic <dam...@apache.org> Date:11/04/2013 02:11 (GMT-05:00) To: Commons Developers List <dev@commons.apache.org> Subject: Re: Backporting try-with-resources to Java < 7 (was: Re: [imaging] Closing stream) For the record, I would only use this for imaging >= 2.0. Weaver looked undocumented and undecipherable to me, but let me look at it again slowly. Damjan On Sun, Nov 3, 2013 at 9:14 PM, Matt Benson <gudnabr...@gmail.com> wrote: > I wasn't under the impression this was blocking imaging 1.0. In any case, > framing Damjan's work as a Weaver module would still use the same work he's > done with ASM and would really only utilize a standard mechanism for > triggering the process. It would also avoid proliferation of multiple maven > plugins with essentially the same mission: post-processing bytecode. > > Matt > On Nov 3, 2013 10:08 AM, "Gary Gregory" <garydgreg...@gmail.com> wrote: > > > On Sun, Nov 3, 2013 at 10:56 AM, Matt Benson <gudnabr...@gmail.com> > wrote: > > > >> Sounds like it would be trivial to frame what you've done here into the > >> context of a Weaver module, for which there exist both a maven plugin > and > >> an Antlib, as well as a need for a near-term release. :-) > >> > > > > and eating our own dog food :) > > > > We may pushing the limits of Dajman's patience for a 1.0 which is long > > overdue. > > > > I suppose D needs to weigh using ASM or [weaver] vs. adjusting the > current > > code with Java 5. > > > > Gary > > > >> > >> Matt > >> On Nov 3, 2013 2:30 AM, "Damjan Jovanovic" <dam...@apache.org> wrote: > >> > >> > On Fri, Oct 25, 2013 at 1:52 PM, Matt Benson <gudnabr...@gmail.com> > >> wrote: > >> > > >> > > On Oct 25, 2013 6:30 AM, "Damjan Jovanovic" <damjan....@gmail.com> > >> > wrote: > >> > > > > >> > > > On Fri, Oct 25, 2013 at 12:36 PM, Jörg Schaible > >> > > > <joerg.schai...@scalaris.com> wrote: > >> > > > > Hi Damjan, > >> > > > > > >> > > > > Damjan Jovanovic wrote: > >> > > > > > >> > > > > [snip] > >> > > > > > >> > > > > Thanks for explanation. > >> > > > > > >> > > > >> We would be able to adapt that for Java < 1.7 by swallowing the > >> > close > >> > > > >> exception instead of calling addSuppressed() on the primary > >> > exception, > >> > > > >> but the show stopper is catching and rethrowing the primary > >> > exception > >> > > > >> (Throwable), which javac < 1.7 refuses to compile because it > >> doesn't > >> > > > >> do "Rethrowing Exceptions with More Inclusive Type Checking" > >> > > > >> ( > >> > > > >> > > > >> > > >> > http://docs.oracle.com/javase/7/docs/technotes/guides/language/catch-multiple.html > >> > > ). > >> > > > >> > >> > > > >> But this would work and always sets succeeded correctly without > >> > > > >> catch/re-throw: > >> > > > >> > >> > > > >> final InputStream is = factoryMethodThatCanThrow(); > >> > > > >> boolean succeeded = false; > >> > > > >> try { > >> > > > >> try { > >> > > > >> is.methodThatCanThrow(); > >> > > > >> } finally { > >> > > > >> } > >> > > > >> succeeded = true; > >> > > > >> } finally { > >> > > > >> closeSafely(!succeeded, is); > >> > > > >> } > >> > > > > > >> > > > > I guess the nested try was unintentionally ;-) > >> > > > > > >> > > > > Cheers, > >> > > > > Jörg > >> > > > > >> > > > Well that actually won't work, because the "succeeded = true;" > will > >> be > >> > > > skipped if there is a "return;" in the inner try. > >> > > > > >> > > > Other than a custom Java compiler, I guess there's no clean way of > >> > > > doing this in Java < 1.7. There's really only option 2 - with > being > >> > > > careful to always set succeeded correctly on all paths out of the > >> try > >> > > > block. Almost like releasing memory in C. > >> > > > > >> > > > >> > > I haven't deeply followed this conversation, but would this be a > >> > candidate > >> > > for a [weaver] module? > >> > > > >> > > Matt > >> > > > >> > > > >> > > >> > [weaver] I am less sure about, but by playing with Objectweb's ASM I > did > >> > manage to compile code with try-with-resources on Java 7, change the > >> class > >> > file version, do some bytecode manipulation to delete calls to > >> > Throwable.addSuppressed(), and get it to work on Java < 7. > >> > > >> > Made it into a Maven plugin and it works well :). Also verified other > >> Java > >> > 7 language features (binary literals, underscores in numeric literals, > >> > strings in switch, diamonds, exception multi-catch and re-throw) work > on > >> > Java < 7 because they're just syntactic sugar. > >> > > >> > It's very small and simple - 143 lines in 1 file. Is it worth adding > as > >> a > >> > new commons project? Or do we not host (projects that contain) Maven > >> > plugins? > >> > > >> > Damjan > >> > > >> > > > > > > > > -- > > E-Mail: garydgreg...@gmail.com | ggreg...@apache.org > > Java Persistence with Hibernate, Second Edition< > http://www.manning.com/bauer3/> > > JUnit in Action, Second Edition <http://www.manning.com/tahchiev/> > > Spring Batch in Action <http://www.manning.com/templier/> > > Blog: http://garygregory.wordpress.com > > Home: http://garygregory.com/ > > Tweet! http://twitter.com/GaryGregory > > >
