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guile/ice-9/stack-catch.scm
2003-04-05 19:15:35 +00:00

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;;; installed-scm-file
;;;; Copyright (C) 2001 Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
;;;; License as published by the Free Software Foundation; either
;;;; version 2.1 of the License, or (at your option) any later version.
;;;;
;;;; This library is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;;; Lesser General Public License for more details.
;;;;
;;;; You should have received a copy of the GNU Lesser General Public
;;;; License along with this library; if not, write to the Free Software
;;;; Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
;;;;
(define-module (ice-9 stack-catch)
:export (stack-catch))
(define (stack-catch key thunk handler)
"Like @code{catch}, invoke @var{thunk} in the dynamic context of
@var{handler} for exceptions matching @var{key}, but also save the
current stack state in the @var{the-last-stack} fluid, for the purpose
of debugging or re-throwing of an error. If thunk throws to the
symbol @var{key}, then @var{handler} is invoked this way:\n
@example
(handler key args ...)
@end example\n
@var{key} is a symbol or #t.\n
@var{thunk} takes no arguments. If @var{thunk} returns normally, that
is the return value of @code{catch}.\n
Handler is invoked outside the scope of its own @code{catch}. If
@var{handler} again throws to the same key, a new handler from further
up the call chain is invoked.\n
If the key is @code{#t}, then a throw to @emph{any} symbol will match
this call to @code{catch}."
(catch key
(lambda ()
(lazy-catch key
thunk
lazy-handler-dispatch))
handler))