[PD-dev] pointer to struct messages

[Martin Peach]

Isidro Gonzalez wrote:
> Say we are programming an external and we have a
> user-defined struct like:
> 
> typedef struct {
>  float dist[8];
>  float ang[8];
>  float gain[8];
> }loudspeakers;
> 
> Is there a way to output and receive
> a pointer to this struct from and to oulets and inlets
> of pd objects and so communicate
> the data between them?


One way would be to convert a text representation of the pointer into a 
symbol and send that:
char buf[9];
/*each byte of the pointer will be printed as two hex characters*/
loudspeakers *pointer_to_loudspeakers;
t_symbol a_symbol;

sprintf(buf, "%p", pointer_to_loudspeakers);
a_symbol = gensym(buf);

Then send a_symbol to other objects.

A symbol method in the receiver would convert the symbol name back into 
a pointer with:
sscanf(s->s_name, "%p", &(void*)pointer_to_loudspeakers);

Another way, that uses no c, would be to load the 24 floats into a table 
and access it by name using [tabread loudspeakers] and [tabwrite 
loudspeakers].

Martin