[PD] question about getdir(Guenter Geiger)'s code

[Thomas O Fredericks]

getdollarzero can get the dollar zero of any parent.
For example, lets say a patch called "top" contains the abstraction 1.
The abstraction 1 contains the abstraction 2.
The abstraction 2 contains the abstraction 3.
Well, with getdollarzero, abstraction 1 through 3 can know the dollar zero
of the patch "top".
The patch "top" becomes the "root" patch.
All the abstractions 1 through 3 have in common this "root" patch.

This is what I needed it for:
1) I am currently developing a state saving system that does not require the
"$0" arguments (of Memento for example). The state of all elements that have
the same "root" patch are saved together.
2) I am also creating a timing architecture for PD and I wanted all elements
in the same "root" to be synchronized together.

Tom



On 8/29/07, Hans-Christoph Steiner <hans at eds.org> wrote:
>
>
> Hey,
>
> I think Günter didn't want to depend on non-public headers like
> g_canvas.h, so included the glist struct from that header.  Personally, I
> think makes more sense to include the g_canvas.h header.
>
> [parentdollarzero] like a useful object, I am not usre what
> [getdollarzero] does beyond [float $0] or [$0].  Anyway, hopefully they make
> into Pd-extended.
>
> .hc
>
>
> On Aug 27, 2007, at 4:43 PM, Thomas O Fredericks wrote:
>
> Thanks to Han's help page (http://puredata.info/docs/developer/mingw) I
> was able to compile a test external on windows with mingw.
>
> I then started making a new external called getdollarzero based on getdir
> (from ggee) and parentdollarzero (from iemlib2). I compiled it and it works
> but I had to:
> 1) remove Guenter's hack from getdir's source code
> 2) and therefore include g_canvas.h
>
> My question is the following: why is there a hack in the first place? If I
> do not use it will my code crash PD in some way (I compiled against PD 0.4and worked fine during testing)?
>
> As a reference, here is my code with the hack commented out :
>
>
> --------- getdollarzero  --------
>
> #include "m_pd.h"
> #include "g_canvas.h" //needed to include g_canvas.h once the hack was
> commented out
>
>
> /* HACK
> struct _glist
> {
>     t_object gl_obj;            // header in case we're a glist
>     t_gobj *gl_list;            // the actual data
>     struct _gstub *gl_stub;     // safe pointer handler
>     int gl_valid;               // incremented when pointers might be
> stale
>     struct _glist *gl_owner;    // parent glist, supercanvas, or 0 if none
> };
>
> END HACK
> */
>
> typedef struct getdollarzero
> {
>     t_object x_ob;
>     t_canvas * x_canvas;
>     t_outlet* x_outlet;
>     int x_level;
> } t_getdollarzero;
>
>
>
>
> static void getdollarzero_bang(t_getdollarzero *x)
> {
>     int i = x->x_level;
>     t_canvas* last = x->x_canvas;
>
>     while (i>0) {
>         i--;
>         if (last->gl_owner) last = last->gl_owner;
>     }
>     // code example taken from iemlib2's parentdollarzero:
>     // x->s_parent_unique = canvas_realizedollar((t_canvas
> *)this_canvas->gl_owner, gensym("$0"));
>     // original get dir function:
>     //outlet_symbol(x->x_outlet,canvas_getdir(last));
>
>     outlet_symbol(x->x_outlet,canvas_realizedollar(last, gensym("$0")));
> }
>
> t_class *getdollarzero_class;
>
> static void *getdollarzero_new(t_floatarg level)
> {
>     t_getdollarzero *x = (t_getdollarzero *)pd_new(getdollarzero_class);
>     x->x_canvas =  canvas_getcurrent();
>     x->x_outlet =  outlet_new(&x->x_ob, &s_);
>     x->x_level  =  level;
>     return (void *)x;
> }
>
> void getdollarzero_setup(void)
> {
>     getdollarzero_class = class_new(gensym("getdollarzero"),
> (t_newmethod)getdollarzero_new, 0,
>         sizeof(t_getdollarzero), 0, A_DEFFLOAT,0);
>     class_addbang(getdollarzero_class, getdollarzero_bang);
> }
>
> --------- getdollarzero  end --------
>
> --
> thomas ouellet fredericks, tof at danslchamp.org, montreal, canada
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>
>
>
> ----------------------------------------------------------------------------
>
> Computer science is no more related to the computer than astronomy is
> related to the telescope.      -Edsger Dykstra
>
>
>


-- 
thomas ouellet fredericks, tof at danslchamp.org, montreal, canada
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