GNU bug report logs - #10581
exit-hook is undocumented and is not called from a non-interactive environment

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From: Ian Price <ianprice90 <at> googlemail.com>
To: Andrew Psaltis <ampsaltis <at> gmail.com>
Cc: 10581 <at> debbugs.gnu.org
Subject: bug#10581: exit-hook is undocumented and is not called from a non-interactive environment
Date: Mon, 23 Jan 2012 02:08:14 +0000

[Message part 1 (text/plain, inline)]

Andrew Psaltis <ampsaltis <at> gmail.com> writes:

> Second:
> When I write a scheme script that adds some function to exit-hook, it
> is not invoked from a non-interactive call to guile.  I have a file
> test.scm that looks like so:
>
> (add-hook! exit-hook (lambda () (display "bye\n")))
>
> In an interactive environment:
>
> $ guile -l test.scm
> guile> (exit)
> bye
> $
>
> In a non-interactive environment:
> $ guile -s test.scm
> $
>
> Nothing is printed.  As far as I can tell, exit-hook should be made
> available in a non-interactive environment so that modules loading
> libraries can cleanup easily.

Assuming exit-hook is supposed to do this, and I would presume it is
meant to. I have a patch which will implement this for
stable-2.0. Basically, I wrap everything in a large catch, and when
guile gets a 'quit exception it runs the exit hooks before throwing the
exception again.

As far as I can see, this covers the case where guile exits normally
either by use of quit/exit, or just by finishing the script. It does
_not_ perform the cleanup if guile quits because of an uncaught
exception, but if someone thinks this is desirable, it should be a
matter of changing the catch.

I'm not quite sure how to add a test case for this though.

-- 
Ian Price

"Programming is like pinball. The reward for doing it well is
the opportunity to do it again" - from "The Wizardy Compiled"

[0001-Run-exit-hook-when-scripts-finish-normally.patch (text/x-patch, inline)]

From baaf226cb91a41de66b7dc663c433c67f1c0f0e5 Mon Sep 17 00:00:00 2001
From: Ian Price <ianprice90 <at> googlemail.com>
Date: Sun, 22 Jan 2012 19:47:16 +0000
Subject: [PATCH] Run exit-hook when scripts finish normally.

* module/ice-9/command-line.scm (compile-shell-switches): Wrap the
  body of the output expression in a catch for `quit' exceptions, so
  that we can run the `exit-hook'.
---
 module/ice-9/command-line.scm |   68 +++++++++++++++++++++-------------------
 1 files changed, 36 insertions(+), 32 deletions(-)

diff --git a/module/ice-9/command-line.scm b/module/ice-9/command-line.scm
index 8aed74e..e33fac8 100644
--- a/module/ice-9/command-line.scm
+++ b/module/ice-9/command-line.scm
@@ -385,38 +385,42 @@ If FILE begins with `-' the -s switch is mandatory.
       `(;; It would be nice not to load up (ice-9 control), but the
         ;; default-prompt-handler is nontrivial.
         (@ (ice-9 control) %)
-        (begin
-          ;; If we didn't end with a -c or a -s and didn't supply a -q, load
-          ;; the user's customization file.
-          ,@(if (and interactive? (not inhibit-user-init?))
-                '((load-user-init))
-                '())
-
-          ;; Use-specified extensions.
-          ,@(map (lambda (ext)
-                   `(set! %load-extensions (cons ,ext %load-extensions)))
-                 user-extensions)
-
-          ;; Add the user-specified load path here, so it won't be in
-          ;; effect during the loading of the user's customization file.
-          ,@(map (lambda (path)
-                   `(set! %load-path (cons ,path %load-path)))
-                 user-load-path)
-
-          ;; Put accumulated actions in their correct order.
-          ,@(reverse! out)
-
-          ;; Handle the `-e' switch, if it was specified.
-          ,@(if entry-point
-                `((,entry-point (command-line)))
-                '())
-          ,(if interactive?
-               ;; If we didn't end with a -c or a -s, start the
-               ;; repl.
-               '((@ (ice-9 top-repl) top-repl))
-               ;; Otherwise, after doing all the other actions
-               ;; prescribed by the command line, quit.
-               '(quit)))))
+        (catch 'quit
+          (lambda ()
+            ;; If we didn't end with a -c or a -s and didn't supply a -q, load
+            ;; the user's customization file.
+            ,@(if (and interactive? (not inhibit-user-init?))
+                  '((load-user-init))
+                  '())
+
+            ;; Use-specified extensions.
+            ,@(map (lambda (ext)
+                     `(set! %load-extensions (cons ,ext %load-extensions)))
+                   user-extensions)
+
+            ;; Add the user-specified load path here, so it won't be in
+            ;; effect during the loading of the user's customization file.
+            ,@(map (lambda (path)
+                     `(set! %load-path (cons ,path %load-path)))
+                   user-load-path)
+
+            ;; Put accumulated actions in their correct order.
+            ,@(reverse! out)
+
+            ;; Handle the `-e' switch, if it was specified.
+            ,@(if entry-point
+                  `((,entry-point (command-line)))
+                  '())
+            ,(if interactive?
+                 ;; If we didn't end with a -c or a -s, start the
+                 ;; repl.
+                 '((@ (ice-9 top-repl) top-repl))
+                 ;; Otherwise, after doing all the other actions
+                 ;; prescribed by the command line, quit.
+                 '(quit)))
+          (lambda args
+            (run-hook exit-hook)
+            (apply throw args)))))
 
       (if (pair? args)
           (begin
-- 
1.7.7.5

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