I've run into this problem before as well. Doesn't changing the signature involve a backwards-incompatible change though?
On Wed, Oct 3, 2018 at 5:11 PM Jeff Klukas <jklu...@mozilla.com> wrote: > I'm working on https://issues.apache.org/jira/browse/BEAM-5638 to add > exception handling options to single message transforms in the Java SDK. > > MapElements' via() method is overloaded to accept either a SimpleFunction, > a SerializableFunction, or a Contextful, all of which are ultimately stored > as a Contextful where the mapping functionis expected to have signature: > > OutputT apply(InputT element, Context c) throws Exception; > > So Contextful.Fn allows throwing checked exceptions, but neither > SerializableFunction nor SimpleFunction do. The user-provided function > has to satisfy the more restrictive signature: > > OutputT apply(InputT input); > > Is there background about why we allow arbitrary checked exceptions to be > thrown in one case but not the other two? Could we consider expanding > SerializableFunction and SimpleFunction to the following?: > > OutputT apply(InputT input) throws Exception; > > This would, for example, simplify the implementation of ParseJsons and > AsJsons, where we have to catch an IOException in MapElements#via only to > rethrow as RuntimeException. >
