Re: Eliminating Singleton Objects

[John W. Eaton]

On 04/28/2017 07:49 PM, Rik wrote:

> Is there a performance issue here?  If you start passing too many
> arguments to a function, more than can conveniently fit into the number
> of scratch registers that your CPU has, then you have to pass arguments
> on the stack which will slow things down.  But I can't quite tell if you
> are suggesting another parameter, or whether you want to include the
> pointer to the interpreter as say the first entry in the
> octave_value_list passed as inputs to the function.  Presumably the
> octave_value_list is already passed as a pointer/reference since it
> could be large.  In that case it wouldn't have an impact.

At first, I thought it would be easier to just add a pointer to the 
interpreter object to the octave_value_list that is passed to functions. 
 But it turned out to be difficult to chase down all the places where 
it is needed.  There are many locations where it could be needed and I 
couldn't figure out an easy way to get help from the compiler.

So I started working on passing the pointer to the interpreter as an 
additional parameter to DEFUN functions.  It seems much cleaner this 
way.  It also means that these functions will now accept three arguments 
instead of two.  One is a pointer to the interpreter, one is a const 
reference to the octave_value_list containing the arguments, and one is 
an int for nargout.  I doubt that passing one additional pointer to 
these functions will make a big difference overall, but we can certainly 
measure it to be sure.

jwe