Annotation to override DbCodec and SqlArrayCodec typeclasses

[AugustNagro]

It's inconvenient to derive a DbCodec when two fields of the same type require different codecs, because the imports conflict. One approach to fix this would be implementing a DbCodecOverride and SqlArrayCodecOverride annotation, like:

/** This annotation allows the user to explicitly select the DbCodec used on a field.
 * It's useful if you have two fields of the same type that require different codecs. For example,
 * assume we have two LongCodecs:
 * {{{
 *   val codecA: DbCodec[Long] = ???
 *   val codecB: DbCodec[Long] = ???
 *
 *   case class MyUser(a: Long, b: Long) derives DbCodec
 * }}}
 *
 * And `codecA` should be used for field `a`, and `codecB` for field b.
 * The normal approach of importing both codecs won't work, since they have the same type and will conflict.
 * Instead, we can do
 *
 * {{{
 *   case class MyUser(
 *     @DbCodecOverride(codecA) a: Long,
 *     @DbCodecOverride(codecB) b: Long
 *   ) derives DbCodec
 * }}}
 *
 * */
class DbCodecOverride[A](val codec: DbCodec[A]) extends StaticAnnotation

#36 (comment)

[Nexus6]

This looks like a workable solution. I personally would prefer a more succinct (and less dramatic) name for the annotation. Something like @DbColumn(codecA) maybe. "Override" suggests that you (the library user) are doing something really weird/crazy/out-of-the-ordinary/dangerous. But the annotation is merely for the purposes of selecting a particular codec when several are available.