Hello all, I just sent a pull request with a style guide for developers of new PTransforms - intended for library writers, e.g. people who contribute new connectors and other transforms to Beam. The guide is mainly based on experience from reviewing connectors contributed by JB and others, but it's intended to be generally applicable.
It covers a variety of points - from code organization, to overall API design, to error handling and so on. I expect most of it to be non-controversial and just reflect the style of existing transforms in Beam - however all of it is, of course, up to debate. https://github.com/apache/beam-site/pull/134/ I'm hoping that this documentation will help guide new transform authors in the right direction from the start, as well as make the job of reviewers easier by providing a source they can link to and helping focus the review on resolving more ambiguous points. (Note that, like all other documentation, this will evolve, so the goal of the current PR is not to be complete, but to be a starting point) When the guide is ratified, I think it'll make sense to file JIRAs to bring Beam in accordance with it - there are a few transforms that were written before the best practices shaped up. Thanks!
