Re: Hook change hook?

[Neil Jerram]

>>>>> "Marius" == Marius Vollmer <address@hidden> writes:

    Marius> Neil Jerram <address@hidden> writes:
    >> When working with hooks, I often find that I have to wrap access to
    >> the hook rather than making the hook available directly, because I
    >> need to do something extra whenever something is added or removed from
    >> that hook.

    Marius> How about goopsifying hooks so that add-hook is a generic function?

I just tried to do this - i.e. making all the primitives in hooks.c
generic except for `make-hook'.  Unfortunately it isn't
straightforward because `add-hook!' has arity (2,1,0), and
create_gsubr_with_generic doesn't support functions with this arity.

I can think of various kludges (e.g. use arity (2,0,1) or (3,0,0)
instead and maybe provide a Scheme wrapper in boot-9.scm).  For a
clean solution I guess we should either add a new scm_tc7_subr_3o type
to the code (scary), or support genericization of cclos (also scary).

Any other ideas?

        Neil

PS. For future reference, here's the SCM_GDEFINE definition that I
added to snarf.h to try this out:

#define SCM_GDEFINE(FNAME, PRIMNAME, REQ, OPT, VAR, ARGLIST, DOCSTRING) \
SCM_SNARF_HERE(\
static const char s_ ## FNAME [] = PRIMNAME; \
static SCM g_ ## FNAME; \
SCM FNAME ARGLIST\
)\
SCM_SNARF_INIT(\
scm_c_define_gsubr_with_generic (s_ ## FNAME, REQ, OPT, VAR, \
                                 (SCM_FUNC_CAST_ARBITRARY_ARGS) FNAME, \
                                 & g_ ## FNAME); \
)\
SCM_SNARF_DOCS(primitive, FNAME, PRIMNAME, ARGLIST, REQ, OPT, VAR, DOCSTRING)