concat bug?

[Mike Hale]

Xbytor, in my notes I have an old post( not sure how old ) from you where you say that sometimes Array.concat() fails in ExtendScipt. Do you know if that has been fixed?

[jacobolus]

I do see this code in xtools:

Code: Select all//
// Stdlib.findFiles is a recursive version of Stdlib.getFiles
//
Stdlib.findFiles = function(folder, mask) {
  var files = Stdlib.getFiles(folder, mask);
  var folders = Stdlib.getFolders(folder);

  for (var i = 0; i < folders.length; i++) {
    var f = folders;
    var ffs = Stdlib.findFiles(f, mask);
    // files.concat(ffs); This occasionally fails for some unknown reason (aka
    // interpreter Bug) so we do it manually instead
    while (ffs.length > 0) {
      files.push(ffs.shift());
    }
  }
  return files;
};

Dunno what the issue was though.

[jacobolus]

I would also be very curious to know if there are issues w/ concat, and under what circumstances and in what PS versions, and what exactly the effects were (wrong output? thrown errors?). It also might be possible to do something like:
Code: Select allvar _tmp; // <-- put at top of function or wherever

((_tmp = arr1.slice(0)), _tmp.push.apply(out, arr2), _tmp)

// to replace

arr1.concat(arr2)
Or even a general-purpose:
Code: Select allvar concat = function () { // accepts any number of arrays
    var i, n, out, push;
    if (arguments.length === 0) { return []; }
    push = Array.prototype.push;
    out = Array.prototype.slice.call(arguments[0], 0); // shallow copy first arg
    for (i = 1, n = arguments.length; i < n; i++) {
        push.apply(out, arguments);
    }
    return out;
};

concat(arr1, arr2, arr3)
Or added to the Array prototype:
Code: Select allArray.prototype.concat2 = function () { // accepts any number of arrays
    var i, n, out, push;
    push = Array.prototype.push;
    out = Array.prototype.slice.call(this, 0); // shallow copy
    for (i = 0, n = arguments.length; i < n; i++) {
        push.apply(out, arguments);
    }
    return out;
};

arr1.concat2(arr2, arr3)
But if concat is broken, then other array methods might also have problems.

[xbytor]

Mike Hale wrote:Do you know if that has been fixed?

I haven't checked in awhile. I noticed the bug back in the CS/SC2 era. I should probably find reproducible test case and find out which versions of PS have the bug.