In the end I choose a different way, maybe not the most elegant yet it works.
Curve*[T] = object
cp*: seq[T]
....
ICurve*[T] = object
cp*: iterator: T
....
func linear*[T](cp: seq[T] or iterator:T): auto =
var curve = when cp is iterator:T:
ICurve[T]()
else:
Curve[T]()
....
proc iterPoint*[T](curve: Curve[T] or ICurve[T], steps:float):auto=
#create an "internal" closure, if needed, to get the same interface for
#sequences and closure iterators as input to iterPoints.
when curve.cp is seq[T]:
func curvePoints (cps:seq[T]): auto=
return iterator(): auto=
for i in cps:
yield i
let cp = curvePoints(curve.cp)
else:
let cp = curve.cp
....
Run
current state of the full code, a curve / spline library, is at
<https://ingoogni.nl/tempstuff/curve.nim.txt> (needs vmath. needs pixie for the
demo.)
I'll have to study the object variants, but the example kind of confused me.
Thanks
