Saving Proc object in C extension


#1

Hi all.

The question is: can I save some Proc object in global variable of C
extension?

What I’ve tried:

static VALUE g_callback;

//some callback-saving function:
static VALUE save_callback(VALUE self, VALUE proc)
{
…bla-bla-bla…

rb_global_variable(&proc); //as recommended in “Extending Ruby”

g_callback = proc;

…bla-bla-bla…
}

But when I’ve tried to use the saved g_callback later, I’ve received
various
errors. Moreover,

rb_p(g_callback);

prints some garbage or crashes (just like object g_callback references
is
deleted). Raw integer value of g_callback remains unchanged.

What I do wrong?

Thanks.

Victor.


#2

“V” == Victor S. removed_email_address@domain.invalid writes:

V> static VALUE save_callback(VALUE self, VALUE proc)
V> {
V> …bla-bla-bla…

V> rb_global_variable(&proc); //as recommended in “Extending Ruby”

proc is on the stack, after the end of save_callback() &proc don’t make
reference to the proc object.

V> What I do wrong?

This is g_callback which must be registered.

static VALUE g_callback;

static VALUE save_callback(VALUE self, VALUE proc)
{
/* … /
g_callback = proc;
/
… */
}

/* … */

void Init_bla_bla_bla()
{
/* … /
g_callback = Qnil;
rb_global_variable(&g_callback);
/
… */
}

Guy Decoux


#3

V> What I do wrong?

This is g_callback which must be registered.

Thanks Guy! I’ve expected rb_global_variable uses only value of proc,
not
address. Now I’ve understand my error.

Thanks!

Guy Decoux

Victor.