[PD-dev] PDINSTANCE for Pd (was Re: call for discussion double-precision file extension)

[Antoine Rousseau]

I very much agree that in the future Pd (and externals) could be always
compiled with PDINSTANCE.

I was thinking to a way for the transition: we could:
- change the t_pdinstance pd_s_* fields to pointers (and adapt the s_*
replacement  macros accordingly),
- export "hidden" globals s_*
- initialize pd_maininstance pd_s_* fields to the global versions.

CURRENT:
/* m_pd.h */
struct _pdinstance
{
    t_symbol  pd_s_float;
}
#define s_float     (pd_this->pd_s_float)

/* m_class.c */
t_pdinstance *pdinstance_init(t_pdinstance *x)
{
    dogensym("float",     &x->pd_s_float,    x);
}

PROPOSAL:
/* m_pd.h */
struct _pdinstance
{
    t_symbol  *pd_s_float;
}
#define s_float     (*(pd_this->pd_s_float))

/* m_class.c */
#undef s_float
t_symbol s_float;
t_pdinstance *pdinstance_init(t_pdinstance *x)
{
    if(x != &pd_maininstance) x->pd_s_float = gensym("float");
    else {
        dogensym("float",     &s_float,    x);
        x->pd_s_float = &s_float;
}

What do you think?

I've tried this (in libpd context) almost successfully, but I've
encountered a problem: the s_float as seen from an app linked to libpd
seems to be uninitialized.
I've tried something simpler:
/* m_class.c */
float myfloat = 10.0;
t_pdinstance *pdinstance_init(t_pdinstance *x)
{
    myfloat = 20.0;
    printf("pdinstance_init::myfloat: %f\n", myfloat);
}

/* pdtest.c */
extern float myfloat;
int main()
{
    libpd_init();
    printf("myfloat: %f\n", myfloat);
}

cc -I../../../libpd_wrapper -I../../../pure-data/src -O3   -c -o pdtest.o
pdtest.c
gcc -o pdtest pdtest.o ../../../libs/libpd.so

$ pdtest
pdinstance_init::myfloat: 20.00000
myfloat: 10.00000

Do you know why pdtest doesn't see the updated value?

Le mer. 30 mars 2022 à 23:51, Christof Ressi <info at christofressi.com> a
écrit :

> AFAICT, the main issue is that multi-instance Pd misses symbols for
> certain global variables, most notably  s_float, s_symbol, s_bang, etc.
>
> The problem is that these are really exported global structs. If they
> were *pointers*, we could simply make them point to the corresponding
> field in the main Pd instance. But in this case I don't really see a
> solution...
>
> On 30.03.2022 18:07, IOhannes m zmoelnig wrote:
> >
> > On 3/30/22 17:45, Dan Wilcox wrote:
> >> I lean much more on the side that PDINSTANCE is a low-level, per
> >> project compile option and not general-purpose. If you are using
> >> libpd, then your environment is a bit more custom anyway.
> >
> > i wonder what the penalty would be to turn on PDINSTANCE on Pd?
> >
> >
> > obviously a problem with externals, but maybe we can come up with some
> > clever hack (under the assumption, that Pd (the app) only runs a
> > single instance, even if compiled with multi-instance support) to use
> > legacy externals - if that is even possible.
> >
> > apart from that?
> >
> > fgadrms
> > IOhannes
> >
> > _______________________________________________
> > Pd-dev mailing list
> > Pd-dev at lists.iem.at
> > https://lists.puredata.info/listinfo/pd-dev
>
>
>
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