+1 with the proposal. Very good initiative ! Thanks Regards JB
On Feb 3, 2017, 15:03, at 15:03, Kenneth Knowles <[email protected]> wrote: >Hi all, > >Right now when you want to use MapElements<A, B> (and friends) you have >two >options: > >1. Use a SimpleFunction Java 7 style > > MapElements.via(SimpleFunction<A, B>() { > @Override > public B return apply(A input) { > return ...expr...; > } > } > >and the type descriptors are automatically inferred > >2. Use a lambda and withOutputType > > MapElements.via((A input) -> ...expr...) > .withOutputType(new TypeDescriptor<B>(){}) > > MapElements.via((A input) -> ...expr...) > .withOutputType(TypeDescriotors.bs()) > >and you might have a handy helper in TypeDescriptors (note the plural) >or >you might have to create your own, which is a weird pattern if you >haven't >seen it before. Both shown above. > >[PROPOSAL] Here is a neat trick for getting type information like in #1 >but >with a lambda like #2 and a bit less verbosity: > > MapElements.via(new SimpleFunction<A, B>((A input) -> ...expr...) {}) > >I think we can add this. I lean towards this just being a third option, >but >could be easily swayed to drop #2. > >This is https://github.com/apache/beam/pull/1855 where you can see some >unit tests demonstrating it more, and take a look at what it means for >error checking, etc. It is backwards-compatible but still a change to a >core API so deserves a thread on list. > >Thoughts? > >Kenn
