[slime-devel] Patch: ISO 8601 Date format for SLIME inspector

[Tom Pierce]

Hi,

I was playing around with the SLIME inspector and I happened to
inspect a slot in a class where I'm storing a universal date.  I
thought it was nifty that the inspector tried to show me the date in
ISO 8601 format.  However, I noticed that the date was wrong.  Instead
of displaying time at "Zulu" as indicated by the Z at the end, it was
displaying the time with respect to my current timezone.  I did some
digging and noticed that the Z was hard coded!  Uh oh!

I decided to try to "fix" this problem and make the inspector display
the proper ISO 8601 time and include the correct timezone.  Thanks to
Nikolai Sandved's ISO 8601 page
(http://www.pvv.ntnu.no/~nsaa/ISO8601.html), this was easy.  I took
his format-iso8601-time and included it in swank.lisp.  Then, I
modified the inspect-for-emacs method that takes an integer to call
his format-iso8601-time function.  VOILA!  Proper dates.

Tom

Index: swank.lisp
===================================================================
RCS file: /project/slime/cvsroot/slime/swank.lisp,v
retrieving revision 1.309
diff -u -r1.309 swank.lisp
--- swank.lisp	21 Jun 2005 18:28:58 -0000	1.309
+++ swank.lisp	23 Jul 2005 21:37:04 -0000
@@ -3659,6 +3659,27 @@
   (declare (ignore inspector))
   (values "A number." `("Value: " ,(princ-to-string n))))
 
+(defun format-iso8601-time (time-value &optional include-timezone-p)
+    "Formats a universal time TIME-VALUE in ISO 8601 format, with the
time zone included if INCLUDE-TIMEZONE-P is non-NIL"
+    
+    ;; Taken from http://www.pvv.ntnu.no/~nsaa/ISO8601.html
+    ;; Thanks, Nikolai Sandved and Thomas Russ!
+    
+    (flet ((format-iso8601-timezone (zone)
+             (if (zerop zone)
+               "Z"
+               (multiple-value-bind (h m) (truncate (abs zone) 1.0)
+                 ;; Tricky.  Sign of time zone is reversed in ISO 8601
+                 ;; relative to Common Lisp convention!
+                 (format nil "~:[+~;-~]~2,'0D:~2,'0D"
+                         (> zone 0) h (round m))))))
+    (multiple-value-bind (second minute hour day month year dow dst zone)
+      (decode-universal-time time-value)
+      (declare (ignore dow dst))
+      (format nil "~4,'0D-~2,'0D-~2,'0DT~2,'0D:~2,'0D:~2,'0D~:[~*~;~A~]"
+              year month day hour minute second
+              include-timezone-p (format-iso8601-timezone zone)))))
+
 (defmethod inspect-for-emacs ((i integer) inspector)
   (declare (ignore inspector))
   (values "A number."
@@ -3671,10 +3692,7 @@
            (label-value-line "Length" (integer-length i))
            (ignore-errors
              (list "As time: " 
-                   (multiple-value-bind (sec min hour date month year)
-                       (decode-universal-time i)
-                     (format nil "~4,'0D-~2,'0D-~2,'0DT~2,'0D:~2,'0D:~2,'0DZ"
-                             year month date hour min sec)))))))
+                   (format-iso8601-time i t))))))
 
 (defmethod inspect-for-emacs ((c complex) inspector)
   (declare (ignore inspector))