Three Monkeys, Three Typewriters, Two Days

Sane way to return arrays to JS from XPCOM methods

With bug 523817 fixed, you can now write an interface like this:

  void getSomething([optional] out unsigned long count,
                    [retval, array, size_is(count)] out whatever outArray);

and js consumers can do:

  var myArr = foo.getSomething();

to get an array without having to have a dummy argument for the length. Word of warning: this only works if the length has no required non-retval arguments after it, so put that length at the end, right before the retval array.