TomlMapper chaining/delegation

[comp500]

I'd like to structure the mappers for my types in a bottom-up way, rather than specifying everything from the top level, and pass various context data down. This is the sort of thing I have currently:

data class IndexFileLoc(
	val file: PackwizPath,
	val hashFormat: String,
	val hash: String,
) {
	companion object {
		fun mapper(base: PackwizPath.Base) = tomlMapper {
			mapping<IndexFileLoc>("hash-format" to "hashFormat")
			val pathMapper = PackwizPath.mapper(base)
			decoder { it: TomlValue.String -> pathMapper.decode<PackwizPath>(it) }
			encoder { it: PackwizPath -> pathMapper.encode(it) }
		}
	}
}

It'd be great if there was a cleaner way to handle this, such as a delegate method that specifies a mapper to delegate mapping of a given type to (or infer from the types encoders/decoders/mappings are specified for?)

[valderman]

I'm not sure I follow. From your example, it looks like you'd want a function TomlMapperConfigurator.delegate<T>(mapper: TomlMapper), or perhaps TomlMapperConfigurator.delegate(typesToDelegate: Set<KType>, mapper: TomlMapper), which would basically inherit transcoding for the given type(s) from the given mapper. Is that right?

[comp500]

Yep, that's right. I'm not sure whether specifying types upfront or having them be inferred would be better; but it's important that decoders/encoders defined in a TomlMapper take precedence over delegated mappers if they are inferred.