Saving Proc object in C extension

[Victor Shepelev]

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.

 

[ts]

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

 

[Victor Shepelev]

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.

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.