Timo should still have the patch! If you want to re-vive the thread, that'd be great. I'd be happy to support it.
On Tue, Aug 18, 2015 at 2:51 PM, Kristoffer Sjögren <sto...@gmail.com> wrote: > Do you have a link to these patches? > > Reading through the thread, I get the feeling they didn't reject the > idea completely. > > Considering there are also other projects (Crunch, Spark, Storm, etc) > that would benefit from this, maybe we can convince them together? > > > On Tue, Aug 18, 2015 at 2:27 PM, Stephan Ewen <se...@apache.org> wrote: > > Yep, Timo wrote the patch, both for OpenJDK and JDT - the JDT one was > > accepted in the end. > > > > > > On Tue, Aug 18, 2015 at 2:09 PM, Robert Metzger <rmetz...@apache.org> > wrote: > >> > >> Exactly, Timo opened the thread. > >> > >> On Tue, Aug 18, 2015 at 2:04 PM, Kristoffer Sjögren <sto...@gmail.com> > >> wrote: > >>> > >>> Yeah, I think I found the thread already... by Timo Walther? > >>> > >>> On Tue, Aug 18, 2015 at 2:01 PM, Stephan Ewen <se...@apache.org> > wrote: > >>> > Would have been great. I had high hopes when I saw the trick with the > >>> > "constant pool", but this is only to make what Flink does already > >>> > applicable > >>> > to non-serializable lambdas. > >>> > > >>> > If you want to help us with this, I'll ping you for some support on > the > >>> > OpenJDK mailing list ;-) > >>> > > >>> > On Tue, Aug 18, 2015 at 1:59 PM, Kristoffer Sjögren < > sto...@gmail.com> > >>> > wrote: > >>> >> > >>> >> I suspected that you already had looked into this, but it was worth > a > >>> >> try. It would make everything so much easier. > >>> >> > >>> >> Thanks for the explanation :-) > >>> >> > >>> >> > >>> >> On Tue, Aug 18, 2015 at 1:50 PM, Stephan Ewen <se...@apache.org> > >>> >> wrote: > >>> >> > Hi Kristoffer! > >>> >> > > >>> >> > I looked through the code as well. In fact, Flink currently uses > the > >>> >> > trick > >>> >> > mentioned for Serializable Lambdas in the gist you sent me. > >>> >> > > >>> >> > This works well for lambdas that return simple types (primitives > or > >>> >> > classes > >>> >> > without generics). The information for the generic parametrization > >>> >> > is > >>> >> > unfortunately really erased, it is in no signature or anything. > >>> >> > > >>> >> > Java has the concept of "generic method signatures", which means > >>> >> > that a > >>> >> > method gets a signature string that includes the generic types. > >>> >> > These > >>> >> > signatures are generated for regular functions, but OpenJDK and > >>> >> > OracleJDK do > >>> >> > not generate them for synthetic methods (like lambdas). > >>> >> > > >>> >> > We tried to submit a patch to OpenJDK to add these generic > >>> >> > signatures to > >>> >> > lambda methods, but they did not like the fact that we try to > figure > >>> >> > out > >>> >> > the > >>> >> > generic types of lambdas. I hope they change their minds at some > >>> >> > point... > >>> >> > > >>> >> > Stephan > >>> >> > > >>> >> > > >>> >> > > >>> >> > > >>> >> > On Tue, Aug 18, 2015 at 11:46 AM, Aljoscha Krettek > >>> >> > <aljos...@apache.org> > >>> >> > wrote: > >>> >> >> > >>> >> >> Unfortunately, this also doesn't work for the same reasons. The > >>> >> >> generic > >>> >> >> types of generic parameters of a lambda are not stored anywhere. > >>> >> >> Stephan > >>> >> >> mentioned to me that the only possibility right now would be to > >>> >> >> look at > >>> >> >> the > >>> >> >> code using something like ASM to find a cast in the code to the > >>> >> >> concrete > >>> >> >> type of the generic parameter. > >>> >> >> > >>> >> >> On Tue, 18 Aug 2015 at 11:35 Kristoffer Sjögren < > sto...@gmail.com> > >>> >> >> wrote: > >>> >> >>> > >>> >> >>> How about https://github.com/jhalterman/typetools? > >>> >> >>> > >>> >> >>> On Tue, Aug 18, 2015 at 11:16 AM, Aljoscha Krettek > >>> >> >>> <aljos...@apache.org> > >>> >> >>> wrote: > >>> >> >>> > Hi Kristoffer, > >>> >> >>> > I'm afraid not, but maybe Timo has some further information. > In > >>> >> >>> > this > >>> >> >>> > extended example we can see the problem: > >>> >> >>> > https://gist.github.com/aljoscha/84cc363d13cf1dfe9364. The > >>> >> >>> > output > >>> >> >>> > is: > >>> >> >>> > > >>> >> >>> > Type is: class > >>> >> >>> > org.apache.flink.examples.java8.wordcount.TypeTest$Thing > >>> >> >>> > class org.apache.flink.examples.java8.wordcount.TypeTest$Thing > >>> >> >>> > Type is: class > >>> >> >>> > org.apache.flink.examples.java8.wordcount.TypeTest$Thing > >>> >> >>> > class org.apache.flink.examples.java8.wordcount.TypeTest$Thing > >>> >> >>> > Type is : > >>> >> >>> > > >>> >> >>> > > >>> >> >>> > > >>> >> >>> > > org.apache.flink.examples.java8.wordcount.TypeTest.org.apache.flink.examples.java8.wordcount.TypeTest$Thing<java.lang.String> > >>> >> >>> > class org.apache.flink.examples.java8.wordcount.TypeTest$Thing > >>> >> >>> > > >>> >> >>> > So with the two lambda calls it does not correctly determine > the > >>> >> >>> > generic > >>> >> >>> > parameter of Thing while it works with the anonymous class. > >>> >> >>> > > >>> >> >>> > I was exited when I saw the example because we've been trying > >>> >> >>> > for so > >>> >> >>> > long to > >>> >> >>> > get this to work. Maybe we have to wait for java 19 to get > this > >>> >> >>> > to > >>> >> >>> > work. ;-) > >>> >> >>> > > >>> >> >>> > Thanks a lot for helping, though. :D > >>> >> >>> > Aljoscha > >>> >> >>> > > >>> >> >>> > On Tue, 18 Aug 2015 at 11:01 Kristoffer Sjögren > >>> >> >>> > <sto...@gmail.com> > >>> >> >>> > wrote: > >>> >> >>> >> > >>> >> >>> >> Hi > >>> >> >>> >> > >>> >> >>> >> Potential fix for writing flink jobs using lamdas without > >>> >> >>> >> Eclipse > >>> >> >>> >> JDT? > >>> >> >>> >> > >>> >> >>> >> https://gist.github.com/aslakhellesoy/3678beba60c109eacbe5 > >>> >> >>> >> > >>> >> >>> >> Cheers, > >>> >> >>> >> -Kristoffer > >>> >> > > >>> >> > > >>> > > >>> > > >> > >> > > >
