error: end: no method for class double

[Lukas Reichlin]

Dear Octave Community

I'm trying to overload "end" for my quaternion package such that the following 
two lines work as expected:

        q = quaternion (eye (3))
        q(1:end)

To do so, I created @quaternion/end.m:

function ret = end (q, k, n)

  ## ret = end (q.w, k, n);
  ## ret = feval ("end", q.w, k, n);
  ret = feval (@end, q.w, k, n);
  ## ret = builtin ("end", q.w, k, n);

endfunction

My plan is to use the "end" of double (q.w is a matrix of type double).
However, none of the four variants seem to work. At least the variant using 
builtin seems to work with Matlab. Did I miss something or shall I file a bug 
report?

Thanks for any hints and best regards,
Lukas