CLASS_ATTR_FLOAT_ARRAY question

Thanks everyone who wrote back. I now have a functional external using a custom getter/setter. However I observed a surprising behavior. Following the documentation model, the getter allocates memory if both *ac and **av are zero. Otherwise it uses existing memory. In my test, existing memory is never used. Rather, any time the attribute is accessed through the inspector I see multiple calls for memory allocation. If I access the attribute by mousing on the left inlet, I see a single memory allocation call.

This surprises me, since I would have thought that memory would only be allocated once. As is, I’m concerned about a possible memory leak, or more likely that my code is written incorrectly. I can send the project off list to anyone who is interested.

TiA for any advice,

Eric


#define OSCIL_MAX_HARMS 1024

// the object component

t_float *a_amplitudes; // user spec harmonic weightings

// memory alloc in new instance routine

x->amplitude_bytes = OSCIL_MAX_HARMS*sizeof(t_float);
x->a_amplitudes = (t_float *)sysmem_newptr(x->amplitude_bytes);

// here are the macros in main()

CLASS_ATTR_FLOAT_ARRAY(c,"amplitudes",0,t_oscil,a_amplitudes, OSCIL_MAX_HARMS);
CLASS_ATTR_ACCESSORS(c, "amplitudes", a_amplitudes_get, a_amplitudes_set);
CLASS_ATTR_CATEGORY(c, "amplitudes", 0, "Waveform");
CLASS_ATTR_LABEL(c, "amplitudes", 0, "Harmonic Amplitudes");
CLASS_ATTR_SAVE(c,"amplitudes",0);

// now the getter

t_max_err a_amplitudes_get(t_oscil *x, void *attr, long *ac, t_atom **av)
{
int i;

if ((*ac)&&(*av)) {
post("memory passed to getter: %ld", *ac);
//memory passed in, use it
} else {
//otherwise allocate memory
*ac = OSCIL_MAX_HARMS;
if (!(*av = (t_atom *)sysmem_newptr(sizeof(t_atom) * (*ac)))) {
*ac = 0;
return MAX_ERR_OUT_OF_MEM;
}
post("memory alloced for getter: %ld", *ac);
}
for(i = 0; i < OSCIL_MAX_HARMS; i++){
atom_setfloat(*av + i,x->a_amplitudes[i]);
}
return MAX_ERR_NONE;
}

Thanks, Joshua.

I’ll have a look at CLASS_ATTR_FLOAT_VARSIZE now. But when I try the above code without the custom getter, the attribute comes in filled with garbage, and is impossible to change either from the inspector or with an “amplitude” message. In any case, it is helpful to know that the memory is freed by the caller, as I had hoped.

Eric

Hi Joshua,

No problem. I can report the same behavior when using CLASS_ATTR_FLOAT_VARSIZE. The good news is that the advertised functionality is in place as long as both getter and setter functions are supplied.

Thanks again,
Eric