> but did not want to use inheritance and methods because it needs heap
> allocation
You are using strings so your objects are doing heap allocations anyway. You
should replace the strings with IDs of the target which got hit / died if you
don't want any heap allocation.
You can of course do something similar to dynamic dispatching without
polymorphism:
type MessageType = enum msgHit, msgDeath, msgDayNight
type Message* = object
textImpl: proc(m: Message): string
case messageType*: MessageType
of msgHit:
target*: string
hp*: int
of msgDeath:
died*: string
of msgDayNight:
isDay*: bool
proc hit*(target: string, hp: int): Message =
Message(messageType: msgHit, target: target, hp: hp,
textImpl: proc(m: Message): string =
"You hit " & m.target & " for " & $m.hp & " HP."
)
proc death*(died: string): Message =
Message(messageType: msgDeath, died: died,
textImpl: proc(m: Message): string =
m.died & " just died."
)
proc dayNight*(isDay: bool): Message =
Message(messageType: msgDayNight, isDay: isDay,
textImpl: proc(m: Message): string =
if m.isDay: result = "The day has just begun."
else: result = "Beware! Night is coming."
)
proc getText*(m: Message): string = m.textImpl(m)
