ice-9/stack-catch.scm

   1 ;;; installed-scm-file
   2
   3 ;;;;    Copyright (C) 2001 Free Software Foundation, Inc.
   4 ;;;;
   5 ;;;; This program is free software; you can redistribute it and/or modify
   6 ;;;; it under the terms of the GNU General Public License as published by
   7 ;;;; the Free Software Foundation; either version 2, or (at your option)
   8 ;;;; any later version.
   9 ;;;;
  10 ;;;; This program is distributed in the hope that it will be useful,
  11 ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 ;;;; GNU General Public License for more details.
  14 ;;;;
  15 ;;;; You should have received a copy of the GNU General Public License
  16 ;;;; along with this software; see the file COPYING.  If not, write to
  17 ;;;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  18 ;;;; Boston, MA 02111-1307 USA
  19 ;;;;
  20
  21 (define-module (ice-9 stack-catch)
  22   :export (stack-catch))
  23
  24 (define (stack-catch key thunk handler)
  25   "Like @code{catch}, invoke @var{thunk} in the dynamic context of
  26 @var{handler} for exceptions matching @var{key}, but also save the
  27 current stack state in the @var{the-last-stack} fluid, for the purpose
  28 of debugging or re-throwing of an error.  If thunk throws to the
  29 symbol @var{key}, then @var{handler} is invoked this way:\n
  30 @example
  31 (handler key args ...)
  32 @end example\n
  33 @var{key} is a symbol or #t.\n
  34 @var{thunk} takes no arguments.  If @var{thunk} returns normally, that
  35 is the return value of @code{catch}.\n
  36 Handler is invoked outside the scope of its own @code{catch}.  If
  37 @var{handler} again throws to the same key, a new handler from further
  38 up the call chain is invoked.\n
  39 If the key is @code{#t}, then a throw to @emph{any} symbol will match
  40 this call to @code{catch}."
  41   (catch key
  42          (lambda ()
  43            (lazy-catch key
  44                        thunk
  45                        lazy-handler-dispatch))
  46          handler))