2007-10-26 John Wiegley <johnw@newartisans.com>

	* eshell/em-unix.el (eshell/diff): Before calling the `diff'
	function, ensure that the third argument is turned into a NIL if
	the string is otherwise completely empty (either no characters, or
	all tabs/spaces).  This fixes a bug from a user who found himself
	unable to customize `diff-switches' and still use Eshell's diff
	command.

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 17c3e0af8c9788918be3859b61cf62bdffc47032..aa8f1460ce1bddaeb949d5c1d1d3666146ebf255 100644 (file)
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,12 @@
+2007-10-26  John Wiegley  <johnw@newartisans.com>
+
+       * eshell/em-unix.el (eshell/diff): Before calling the `diff'
+       function, ensure that the third argument is turned into a NIL if
+       the string is otherwise completely empty (either no characters, or
+       all tabs/spaces).  This fixes a bug from a user who found himself
+       unable to customize `diff-switches' and still use Eshell's diff
+       command.
+
 2007-10-26  Glenn Morris  <rgm@gnu.org>
 
        * emacs-lisp/bytecomp.el (byte-compile-warnings): Autoload the

diff --git a/lisp/eshell/em-unix.el b/lisp/eshell/em-unix.el
index 850d51dcac53df0c64d3dd34033741367b80c9a0..384fa0839476246d8cc260ec8c6b65d85caf97ef 100644 (file)
--- a/lisp/eshell/em-unix.el
+++ b/lisp/eshell/em-unix.el
@@ -974,6 +974,13 @@ Show wall-clock time elapsed during execution of COMMAND.")
   (if eshell-diff-window-config
       (set-window-configuration eshell-diff-window-config)))
 
+(defun nil-blank-string ( string )
+  "if a string is all blanks return nil, if there are non-blank characters
+return the string"
+  (cond
+   ((string-match "[^[:blank:]]" string ) string)
+   (nil)))
+
 (defun eshell/diff (&rest args)
   "Alias \"diff\" to call Emacs `diff' function."
   (let ((orig-args (eshell-stringify-list (eshell-flatten-list args))))
@@ -995,7 +1002,8 @@ Show wall-clock time elapsed during execution of COMMAND.")
          (setcdr (last args 3) nil))
        (with-current-buffer
            (condition-case err
-               (diff old new (eshell-flatten-and-stringify args))
+               (diff old new
+                     (nil-blank-string (eshell-flatten-and-stringify args)))
              (error
               (throw 'eshell-replace-command
                      (eshell-parse-command "*diff" orig-args))))