Re: object behavior with Octave...

[Ben Abbott]

James,

I'm not as familiar with Octave's objects as are others. You'll likely  
get much better more (and I expect better) information if your reply- 
all so that thread stays on the list.

I haven't tried this, but I'd create a m-file function called  
create_ball.m and place all the contents below in it.

function ball = create_ball ()
  ball.bounce = @bounce;
  ball.add_volume = @add_volume;
  ball.set_color = @set_color;
endfunction
function ret = bounce (varargins)
... bounce code here ...
endfunction
function ret = add_volumne (varargins)
... add the volume here ...
endfunction
function ret = set_color (varargins)
... set the color here ...
endfunction

The problem I see is that you'll need to access these function as  
ball.bounce(ball)

Perhaps there is a way to associate a handle with a specific instance  
of a structure, but I don't know how.

Do I understand your intention?

Ben

On Feb 14, 2009, at 11:58 AM, James Moliere wrote:

> Ben,
> Thanks!  For the tip below.  I need to keep everything in functions  
> (or
> structures).
>
> I'd really like 1 .m file to hold multiple functions that a user can
> call.  Since Octave does not have the concept of a namespace or  
> package,
> it is possible to create LOTS of .m files but over time, it will be
> difficult manage.
>
> To give a more concrete example, I'd like to use a structure as an
> object such as Ball.  I could create functions like bounce(),
> addVolume(air), setColor(color), etc.  I would also like a .m file  
> named
> createBall.m that returns the structure and it's respective methods  
> for
> a ball.
>
> I'm looking at the docs in the 'GNU Octave Manual 3.3' and am not
> finding anything satisfactory.
>
>
> James
>
> On Sat, 2009-02-14 at 08:34 -0800, Ben Abbott wrote:
> >         
> > On Feb 14, 2009, at 9:54 AM, James Moliere wrote:
> >
> > > looking at the URL
> > > http://asis.epfl.ch/SCI.MATH/octave-2.0.16/Octave-FAQ_3.html
> > >
> > > I don't see the capability below.  Can I assign functions to  
> > > variables
> > > in a structure and call them?
> > >
> > >
> > > # simple increment example
> > > function [ ret ] = tt (a)
> > >       x.a=a
> > >       function result = anon(x)
> > >               x.a = x.a+1
> > >               result = x
> > >       endfunction
> > >       x.increment = @anon
> > >       ret = x
> > > endfunction
> > >
> > > ... I'd like to do something like this
> > >
> > > k = tt(1)
> > > k.increment(k) % or k.increment() without passing in k
> > > ... I'd expect an answer of 2.
> >
> >
> > Your example can be entered at the command line as ...
> >
> > function result = anon(x)
> >        x.a = x.a+1;
> >        result = x;
> > endfunction
> > function [ ret ] = tt (a)
> >        x.a=a;
> >        x.increment = @anon;
> >        ret = x;
> > endfunction
> >
> > x.a = 0;
> >
> > anon(x)
> > ans =
> > {
> >   a =  1
> > }
> >
> > x = tt(1)
> > x =
> > {
> >   a =  1
> >   increment =
> >
> > anon
> > }
> >
> > x.increment(x)
> > ans =
> > {
> >   a =  2
> >   increment =
> >
> > anon
> > }
> >
> > If you try x.increment() it will produce an error, because that is  
> > the
> > same as calling anon().
> >
> > Ben