[PD-dev] Using pd_bind and pd_findbyclass to access data from another external
Christof Ressi
info at christofressi.com
Wed Jan 20 02:21:44 CET 2021
> You also need to be sure that the first class is loaded before, like:
> [declare -lib sender -lib receiver]
> else the receiver object won't load because of link error due to
> missing symbol "send_test_class".
Ugh, one more reason for having all objects in a single binary :-)
On 19.01.2021 23:31, Antoine Rousseau wrote:
> hi,
>
> I would say the problem comes from you declaring send_test_class as
> static in both files, so 2 independent variables are created.
>
> What you can do is declaring send_test_class without "static" in the
> first file:
> t_class *send_test_class;
>
> then using the "extern" keyword in the second file:
> extern t_class *send_test_class;
>
> Even better, you could create a header file like
> "sender_test_class.h", in which you put both the "extern" class
> declaration and
> the definition of the t_send_test structure, so you don't have to
> repeat yourself (you'll still need to actually declare the class,
> without "extern", in the first file).
>
> You also need to be sure that the first class is loaded before, like:
> [declare -lib sender -lib receiver]
> else the receiver object won't load because of link error due to
> missing symbol "send_test_class".
>
> Le mar. 19 janv. 2021 à 21:39, Miller Puckette via Pd-dev
> <pd-dev at lists.iem.at <mailto:pd-dev at lists.iem.at>> a écrit :
>
> That's indeed the difference - a c object like "send_test_class" can't
> be shared beteen different object modules loaded separately into
> Pd. This
> is one reason people have sometimes put multiple externals into a
> single
> object file.
>
> You could have both externs have the same "family name" (like
> "array define" and "array set") - then they can both be defined in the
> same C object file "binarytree.[extent]".
>
> cheers
> Miller
>
> On Tue, Jan 19, 2021 at 11:38:22AM -0800, Eric Lennartson wrote:
> > Hello all,
> >
> > I've been working on trying to send data between different
> externals, but
> > I'm not doing something quite right. I've looked at the code in
> d_global.c
> > as well as for send and receive.
> > The only difference I can see is that mine is not all in the
> same .c file
> > while in the pd source it is.
> >
> > Here's the external with the data. Just an int for now, but it
> will be
> > holding a binary tree later.
> >
> > static t_class *send_test_class;
> > typedef struct _send_test {
> > t_object x_obj;
> > t_symbol* name;
> > int value;
> > }t_send_test;
> >
> > static void *send_test_new(t_symbol *s, t_floatarg f) {
> > t_send_test *x = (t_send_test *)pd_new(send_test_class);
> > x->name = s;
> > x->value = f;
> > pd_bind(&x->x_obj.ob_pd, s); // bind to the name we're given
> > post("send_test created with name %s, and value %d",
> x->name->s_name,
> > x->value);
> > return(x);
> > }
> >
> > static void send_test_free(t_send_test *x) {
> > pd_unbind(&x->x_obj.ob_pd, x->name); // unbind when deleted
> > }
> >
> > void send_test_setup(void) {
> > send_test_class = class_new(gensym("send_test"),
> > (t_newmethod)send_test_new,
> > (t_method)send_test_free,
> > sizeof(t_send_test),
> > CLASS_NOINLET,
> > A_DEFSYM,
> > A_DEFFLOAT,
> > 0);
> > }
> >
> > And here's the receiver.
> >
> > static t_class *send_test_class;
> >
> > static t_class *rcv_test_class;
> >
> > typedef struct _send_test {
> > t_object x_obj;
> > t_symbol* name;
> > int value;
> > }t_send_test;
> >
> > typedef struct _rcv_test {
> > t_object x_obj;
> > t_symbol* name;
> >
> > int value;
> > } t_rcv_test;
> >
> > static void *rcv_test_new(t_symbol *s) {
> > t_rcv_test *x = (t_rcv_test *)pd_new(rcv_test_class);
> > x->name = s;
> > t_send_test* sender = (t_send_test*)pd_findbyclass(x->name,
> > send_test_class);
> >
> > x->value = sender->value;
> > post("sender value is %d", sender->value);
> > post("rcv_test created with name %s, and value %d",
> x->name->s_name,
> > x->value);
> > return(x);
> > }
> >
> > static void rcv_test_free(t_rcv_test *x) {}
> >
> > void rcv_test_setup(void) {
> > rcv_test_class = class_new(gensym("rcv_test"),
> > (t_newmethod)rcv_test_new,
> > (t_method)rcv_test_free,
> > sizeof(t_rcv_test),
> > CLASS_NOINLET,
> > A_DEFSYM,
> >
> > 0);
> > }
> >
> > What exactly is it that I'm doing wrong?
>
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