Question

It looks that ‘smart-operator’ minor mode is very interesting. The .el could help c programmer to add spaces embrace some kinds of operators, such as turning ‘a+b’ to ‘a + b’. I just gave a shot on it. Except the following problem, it works well. Here is the situation.

As to ‘-‘ operator, it could be used in both ‘a – b’ and ‘-1’, ‘-ENOMEM’ cases. Smart-operator covers the first use case. However, it doesn’t work with the latter. Here is the code related to this part.

(defun smart-operator-- ()
  "See `smart-operator-insert'."
  (interactive)
  (cond ((and c-buffer-is-cc-mode (looking-back "\\- *"))
         (when (looking-back "[a-zA-Z0-9_] +\\- *")
           (save-excursion
             (backward-char 2)
             (delete-horizontal-space)))
         (smart-operator-insert "-" 'middle)
         (indent-according-to-mode))
        (t
         (smart-operator-insert "-"))))

How could I modify the code to get it worked with ‘-ENOMEM’ case?

Answer 1

Finally, I got some time to work on this issue. Having the small problem fixed in smart-operator.el is just fun. Paste the patch here for anyone who had the same problem.

--- a/smart-operator.el 2012-11-10 16:25:27.393138909 +0900
+++ b/smart-operator.el 2012-11-10 18:22:18.281490742 +0900
@@ -307,6 +307,10 @@
              (delete-horizontal-space)))
          (smart-operator-insert "-" 'middle)
          (indent-according-to-mode))
+   ((and c-buffer-is-cc-mode (looking-back "[*/%+(><=&^|] *"))
+    (smart-operator-insert "-" 'before))
+   ((and c-buffer-is-cc-mode (looking-back "\\(return\\) *"))
+    (smart-operator-insert "-" 'before))
         (t
          (smart-operator-insert "-"))))

All these cases are covered by the patch.

a = -b;
a + -b;
<other binary operators>
return -ENOMEM;