So final version from my first post would now look like:
(I took variantp from andrea's patty and added my version of match)
template match*(t: typed, handlers: openArray): untyped =
var x = ord(t.kind)
handlers[x](t)
message.nim
import patty
variantp Message:
msgHit(target: string, hp: int)
msgDeath(died: string)
msgDayNight(isDay: bool)
# normally queue
var messages*: Message
proc getTextHit(m: Message): string = "You hit " & m.target & " for " &
$m.hp & " HP."
proc getTextDeath(m: Message): string = m.died & " just died."
proc getTextDayNight(m: Message): string =
if m.isDay:
result = "The day has just begun."
else:
result = "Beware! Night is coming."
proc getText*(m: Message): string =
match(m, [getTextHit, getTextDeath, getTextDayNight])
main.nim
from message import msgDayNight, messages, getText
# game time system
proc informAboutDay() =
messages = msgDayNight(isDay = true)
# player informer
proc update() =
echo( getText(messages) )
when isMainModule:
informAboutDay()
update()
Sweet. Except two things. First andrea's version is complicated and I do not
understand it, so if by accident it stops working with new version of nim i am
doomed. Second, I do not understand how my simple _match_ version is working,
even though I wrote it and it is working...
BTW: Is it possible instead of playing with AST in macros to spit just code
built from strings? Like in static block i could create few lines of code which
would be then compiled as rest of normal code? I know, this is wrong approach
and AST is proper but still...
