test_exports.nim

import interfaced

type
  PokemonType* {.pure.} = enum
    Fire, Psychic # ...

  Charmander* = ref object
  Espeon* = ref object

proc makeNoise*(this: Charmander): string = "Charmander, Charmander"
proc legs*(this: Charmander): int = 2
proc greet*(this: Charmander, other: string): string = "Charmander, Char, Charmander... (" & other & ")"

proc makeNoise*(this: Espeon): string = "By using Telepathy I'm able to communicate with creatures of other species"
proc legs*(this: Espeon): int = 4
proc greet*(this: Espeon, other: string): string = "What a pleasure to meet you, " & other

createInterface *Pokemon: # the * has to come before the name, due to limitations in Nim's lexer(as far as I know)
  proc name*(this: Pokemon): string # the visibility of each method is set individually
  proc typ*(this: Pokemon): PokemonType

proc name*(this: Espeon): string = "Espeon"
proc typ*(this: Espeon): PokemonType = PokemonType.Psychic

proc name*(this: Charmander): string = "Charmander"
proc typ*(this: Charmander): PokemonType = PokemonType.Fire

createInterface *LogSink:
  proc log*(self: LogSink, msg: string)
  proc messagesWritten(self: LogSink): int

proc echoSinkState*(sink: LogSink) =
  echo sink.messagesWritten()