Re: More efficient MEX or MEX-like interface

[David Bateman]

John W. Eaton wrote:
> | It would be good is we could also have a use methods like
> | 
> | const mxArray *
> | octave_matrix::as_mxArray (void) const
> | {
> |   mxArray *retval = new mxArray (mxDOUBLE_CLASS, dims (), mxREAL);
> |   retval.set_data (matrix.fortran_vec ());
> |   return retval;
> | }
> |  
> | and we'd need an appropriate const version of set_data added to the mex 
> | interface. Is this possible or am I missing something?
>
> Yes, you could get the data this way without having to copy if you
> promise not to change the data through the pointer that is returned
> (that's what the const qualifier here will do, yes?).  So that can
> help to improve efficiency for an extended MEX interface, but not for
> the original MEX interface (as I recall, anyway).

As far as I can see we then also need a

  const mxArray *mex::make_value (const octave_value& ov)
  {
    return new mxArray (ov);
  }

method and then need to modify mex.cc (call_mex) such that the "argin" 
variable is const if "V4" is not defined. So I don't really see why at 
least this little modification isn't possible as it would give a 
significant speed up.

D.



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