Forum: IronRuby How to iterate through a C# IEnumerable from IronRuby?

Announcement (2017-05-07): is now read-only since I unfortunately do not have the time to support and maintain the forum any more. Please see and for other Rails- und Ruby-related community platforms.
Doug B. (Guest)
on 2011-05-24 17:29
(Received via mailing list)
Apologies if this is a basic Ruby question. I have a C# method:

public class Myro {
  public static IEnumerator getPixels(Picture picture) {
    for (int x=0; x < picture.width; x++) {
      for (int y=0; y < picture.height; y++) {
          yield return picture.getPixel(x, y);

I can call this fine in IronPython:

for pixel in getPixels(pic):
    r, g, b = getRGB(pixel)
    gray = (r + g + b)/3
    setRGB(pixel, gray, gray, gray)

But I don't see how to call this from IronRuby:

Myro::getPixels(pic) do |pixel|
    r, g, b = Myro::getRGB pixel
    gray = (r + g + b)/3
    Myro::setRGB(pixel, gray, gray, gray)

All I get back is Myro+<getPixels>c__Iterator0.

What do I need to do to actually get each pixel in IronRuby and
process it? Do I need an extension method, perhaps called "each"? If
so, can someone point me to some code?

Thanks in advance for any help,

James S. (Guest)
on 2011-05-24 20:28
(Received via mailing list)

If you change the return type of getPixels to IEnumerable, then this

    Myro::getPixels(pic).each do |pixel|

And arguably it should be IEnumerable rather than IEnumerator, as an
IEnumerable.GetEnumerator() gives you an IEnumerator.

Your code example passes a closure to the getPixels method, which just
gets ignored (all Ruby methods syntactically accept a block/closure,
and they can choose to use it), and returns the IEnumerator.

IronRuby today doesn't support mapping Ruby's Enumerable module to
IEnumerator objects, since it's kind awkward to return an IEnumerator
rather than an IEnumerable from a public API, but since IronPython
sets a precedence for supporting it we should look into it. Opened

This topic is locked and can not be replied to.