If you look at the image package here http://golang.org/src/pkg/image/image.go you can see that the implementation of Opaque() for every image does the same thing, differing only in the pixel-specific logic.
Is there a reason for this? Would any general solution be less efficient? Is it just an oversight? Is there some limitation (I cannot see one) to the type system that would make a polymorphic [was: generic] approach difficult?
[edit] The kind of solution I was thinking of (which does not need generics in the Java sense) would be like:
type ColorPredicate func(c image.Color) bool;
func AllPixels (p *image.Image, q ColorPredicate) bool {
var r = p.Bounds()
if r.Empty() {
return true
}
for y := r.Min.Y; y < r.Max.Y; y++ {
for x := r.Min.X; x < r.Max.X; x++ {
if ! q(p.At(x,y)) {
return false
}
}
}
return true
}
but I am having trouble getting that to compile (still very new to Go - it will compile with an image, but not with an image pointer!).
Is that too hard to optimise? (you would need to have function inlining, but then wouldn't any type checking be pulled out of the loop?). Also, I now realise I shouldn't have used the word "generic" earlier - I meant it only in a generic (ha) way.