Patch for printing of system-error exceptions

Patch for printing of system-error exceptions

[Krister Svanlund]

[-- Attachment #1: Type: text/plain, Size: 176 bytes --]

Wrote a really small patch for proper printing of system-error
exceptions. I'm fairly certain it should work for most cases where it
is thrown by guile.

The patch is attached

[-- Attachment #2: guile-system-error-printer.patch --]
[-- Type: application/octet-stream, Size: 1445 bytes --]

diff --git a/module/ice-9/boot-9.scm b/module/ice-9/boot-9.scm
index 14dfb60..e5603d2 100644
--- a/module/ice-9/boot-9.scm
+++ b/module/ice-9/boot-9.scm
@@ -925,6 +925,14 @@ information is unavailable."
              (_ (default-printer)))
            args))
 
+  (define (system-error-printer port key args default-printer)
+    (apply (case-lambda
+             ((func fmt reasons _) 
+              (format port "System error:\n")
+              (apply format port fmt reasons))
+             (_ (default-printer)))
+           args))
+
   (define (getaddrinfo-error-printer port key args default-printer)
     (format port "In procedure getaddrinfo: ~a" (gai-strerror (car args))))
 
@@ -941,12 +949,13 @@ information is unavailable."
   (set-exception-printer! 'regular-expression-syntax scm-error-printer)
   (set-exception-printer! 'signal scm-error-printer)
   (set-exception-printer! 'stack-overflow scm-error-printer)
-  (set-exception-printer! 'system-error scm-error-printer)
   (set-exception-printer! 'try-again scm-error-printer)
   (set-exception-printer! 'unbound-variable scm-error-printer)
   (set-exception-printer! 'wrong-number-of-args scm-error-printer)
   (set-exception-printer! 'wrong-type-arg scm-error-printer)
 
+  (set-exception-printer! 'system-error system-error-printer)
+
   (set-exception-printer! 'syntax-error syntax-error-printer)
 
   (set-exception-printer! 'getaddrinfo-error getaddrinfo-error-printer))

Re: Patch for printing of system-error exceptions

[Andy Wingo]

Hi Krister,

On Sat 28 Jul 2012 16:39, Krister Svanlund <krister.svanlund@gmail.com> writes:

> +  (define (system-error-printer port key args default-printer)
> +    (apply (case-lambda
> +             ((func fmt reasons _) 
> +              (format port "System error:\n")
> +              (apply format port fmt reasons))
> +             (_ (default-printer)))
> +           args))
> +

Is this actually an improvement?  We miss out on the "func" argument.
Can you show examples before and after this change?

Andy
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