com-lihaoyi / upickle

uPickle: a simple, fast, dependency-free JSON & Binary (MessagePack) serialization library for Scala
https://com-lihaoyi.github.io/upickle
MIT License
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Simplify enum derivation in Scala 3 #453

Closed lihaoyi closed 1 year ago

lihaoyi commented 1 year ago

This PR allows a simple derives call to work on Scala 3 enums.

We add a new macroRWAll macro, that derives now forwards to. This can be called once on each sealed trait or enum and will automatically generate the macroR calls on all the sub-classes. We then add a pair of superTypeReader/superTypeWriter forwarders to allow sub-classes to make use of super-class readers and writers automatically without any input from the user.

Note that this approach does not work in Scala 2; while macroRWAll can be defined, superTypeReader/superTypeWriter seem to cause diverging implicit expansions. So for now I leave the Scala 2 experience unchanged