From: Marius Vollmer <mvo@zagadka.ping.de>
Cc: guile-user@gnu.org
Subject: Re: [guile/scwm] SCM_HOOKP changed?
Date: 16 Sep 2002 01:59:21 +0200 [thread overview]
Message-ID: <87n0qin6sm.fsf@zagadka.ping.de> (raw)
In-Reply-To: <200209151501.24373.pieter.pareit@planetinternet.be>
P Pareit <pieter.pareit@planetinternet.be> writes:
> Hey,
>
> I have a lot of code depending on SCM_HOOKP, has SCM_HOOKP changed
> in any way? I also seen it is not documented, so I guess it should
> not be used, is scm_hook_p the right alternative?
No, the problem is something else.
SCM_HOOKP returns a C boolean, that is, either 0 or 1. scm_hook_p
returns a Scheme boolean, either SCM_BOOL_F or SCM_BOOL_T (which are
both true in the C sense).
In your program belowe, error_hook is a variable, not a hook. Both
SCM_HOOKP and scm_hook_p returne their variant of false, but you test
the return value of scm_hook_p in the wrong way. You would have to
write
if (SCM_FALSEP (scm_hook_p (error_hook)))
...
(Do not compare directly with SCM_BOOL_F since there might be other
false values, like scm_lisp_nil.)
The reason why error_hook is a variable is because scm_c_define
returns the variable that it has created or reused, not the value that
the variable is initialized with.
The best think to do is probably to use SCM_SNARF_HERE and
SCM_SNARF_INIT, like so:
#define SCWM_GLOBAL_HOOK(var, name, args, docstring) \
SCM_SNARF_HERE (SCM var) \
SCM_SNARF_INIT ( \
var = scm_permanent_object (scm_make_hook(SCM_MAKINUM(args))); \
scm_c_define (name, var);)
Guile will support SCM_SNARF_HERE and SCM_SNARF_INIT, I think there is
no way around that. When possibly, I'll also add
backwards-compatability for SCM__I, etc.
--
GPG: D5D4E405 - 2F9B BCCC 8527 692A 04E3 331E FAF8 226A D5D4 E405
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prev parent reply other threads:[~2002-09-15 23:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-15 13:01 [guile/scwm] SCM_HOOKP changed? P Pareit
2002-09-15 20:56 ` Thien-Thi Nguyen
2002-09-15 21:28 ` Thien-Thi Nguyen
2002-09-16 4:39 ` Thien-Thi Nguyen
2002-09-16 9:50 ` Marius Vollmer
2002-09-16 11:35 ` Thien-Thi Nguyen
2002-09-19 20:20 ` Neil Jerram
2002-09-15 23:59 ` Marius Vollmer [this message]
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