Re: scm_create_hook

[Dirk Herrmann]

On 27 May 2001, Michael Livshin wrote:

> SCM
> scm_create_hook (const char *name, int n_args)
> {
>   SCM hook = make_hook (SCM_MAKINUM (n_args), "scm_create_hook");
>   scm_c_define (name, hook);
>   scm_protect_object (hook);
>   return hook;
> }
> 
> question: what the call to `scm_protect_object' is there for?  there's
> no corresponding call to `unprotect' anywhere, and I thought
> `scm_c_define' should hold onto the value anyway?

AFAIK, scm_create_hook is only used in gc.c, and the function seems to be
designed exactly for the way it is used there:  The need to protect the
freshly created hook comes from the fact, that in gc.c the hook is stored
in a global SCM variable.  scm_c_define itself does not make the object
protected, because as soon as the binding is overridden, the object may be
collected.

I think that scm_create_hook should be removed (standard postfix: after a
phase of deprecation :-).  The only place where it is used in guile is
gc.c.  With the existence of scm_gc_register_root the call of
scm_protect_object will become unnecessary, and the remaining
functionality is better placed directly into the initializing code at
gc.c.

Best regards,
Dirk Herrmann