diff options
Diffstat (limited to 'modules/custom-line-paragraph.el')
| -rw-r--r-- | modules/custom-line-paragraph.el | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/modules/custom-line-paragraph.el b/modules/custom-line-paragraph.el index 27f24cfe2..0eb1e2a52 100644 --- a/modules/custom-line-paragraph.el +++ b/modules/custom-line-paragraph.el @@ -54,8 +54,15 @@ (defun cj/duplicate-line-or-region (&optional comment) "Duplicate the current line or active region below. -Comment the duplicated text when optional COMMENT is non-nil." +Comment the duplicated text when optional COMMENT is non-nil. +Signal `user-error' when COMMENT is non-nil but the current mode has +no `comment-start' (e.g. `fundamental-mode'), since commenting would +produce malformed output silently." (interactive "P") + (when (and comment (not (and (stringp comment-start) + (> (length comment-start) 0)))) + (user-error + "Cannot comment in %s: no comment syntax defined" major-mode)) (let* ((b (if (region-active-p) (region-beginning) (line-beginning-position))) (e (if (region-active-p) (region-end) (line-end-position))) (lines (split-string (buffer-substring-no-properties b e) "\n"))) |