Interesting Scala print solution, doesn't work in 2.7.7?

Question

I am trying to create some image algebra code that can work with images (mostly linear pixel buffer + sizes) that have different types for a pixel. To make this work, I defined a parameterized Pixel tag with several methods that should be available for use with any Pixel subclass. (At the moment, I'm only interested in operations that work with the same type of pixels.) Here it is:

trait Pixel[T <: Pixel[T]] {
    def div(v: Double): T
    def div(v: T): T
}

Now I define one type of pixel that has storage based on three doubles (mostly RGB 0.0-1.0), I called it TripleDoublePixel:

class TripleDoublePixel(v: Array[Double]) extends Pixel[TripleDoublePixel] {

    var data: Array[Double] = v

    def this() = this(Array(0.0, 0.0, 0.0))

    def div(v: Double): TripleDoublePixel = {
        new TripleDoublePixel(data.map(x => x / v))
    }

    def div(v: TripleDoublePixel): TripleDoublePixel = {
        var tmp = new Array[Double](3)
        tmp(0) = data(0) / v.data(0)
        tmp(1) = data(1) / v.data(1)
        tmp(2) = data(2) / v.data(2)
        new TripleDoublePixel(tmp)
    }

}

Then we define the image using pixels:

class Image[T](nsize: Array[Int], ndata: Array[T]) {

    val size: Array[Int] = nsize
    val data: Array[T] = ndata

    def this(isize: Array[Int]) {
        this(isize, new Array[T](isize(0) * isize(1)))
    }

    def this(img: Image[T]) {
        this(img.size, new Array[T](img.size(0) * img.size(1)))
        for (i <- 0 until img.data.size) {
            data(i) = img.data(i)
        }
    }

}

( , , , , .)

, , , . :

def idiv[T](a: Image[T], b: Image[T]) {
    for (i <- 0 until a.data.size) {
        a.data(i) = a.data(i).div(b.data(i))
    }
}

, :

(fragment of lindet-gen.scala):145:
error: value div is not a member of T
                 a.data(i) = a.data(i).div(b.data(i))

# scala, - , 2.8. 2.8-rc1, RC1 . 2.7.7?

Answer 1

idiv , .

def idiv[T <: Pixel[T]](a: Image[T], b: Image[T]) {
    for (i <- 0 until a.data.size) {
        a.data(i) = a.data(i).div(b.data(i))
    }
}

T T, , , div. , , Pixel s.

( , Image, , - , , )