Generated markdown in message buffer

[cruegge]

The markdown function uses shell-command-on-region, which in addition to writing to the destination buffer, apparently also prints the output to the echo area and the *Messages* buffer. Maybe call-process-region or something similar should be used instead.

[syohex]

I suppose markdown-mode can avoid this issue by calling call-process-region directly or using start-process(or start-file-process) interfaces.

Use call-process-region directly

diff --git a/markdown-mode.el b/markdown-mode.el
index bad960d..59fcdfa 100644
--- a/markdown-mode.el
+++ b/markdown-mode.el
@@ -5270,8 +5270,15 @@ Return the name of the output buffer used."
                          output-buffer-name)))
        ;; Pass region to `markdown-command' via stdin
        (t
-        (shell-command-on-region begin-region end-region markdown-command
-                                 output-buffer-name))))
+        (let ((buf (get-buffer-create output-buffer-name)))
+          (with-current-buffer buf
+            (setq buffer-read-only nil)
+            (erase-buffer))
+          (let ((ret (call-process-region begin-region end-region
+                                          shell-file-name nil buf nil
+                                          shell-command-switch markdown-command)))
+            (unless (zerop ret)
+              (error "Failed: '%s'" markdown-command)))))))
     output-buffer-name))

 (defun markdown-standalone (&optional output-buffer-name)

Using start-process

This is asynchronous execution.

diff --git a/markdown-mode.el b/markdown-mode.el
index bad960d..8573698 100644
--- a/markdown-mode.el
+++ b/markdown-mode.el
@@ -5270,8 +5270,16 @@ Return the name of the output buffer used."
                          output-buffer-name)))
        ;; Pass region to `markdown-command' via stdin
        (t
-        (shell-command-on-region begin-region end-region markdown-command
-                                 output-buffer-name))))
+        (let ((buf (get-buffer-create output-buffer-name)))
+          (with-current-buffer buf
+            (setq buffer-read-only nil)
+            (erase-buffer))
+          (let ((input (buffer-substring-no-properties begin-region end-region))
+                (proc (start-process-shell-command "markdown" buf markdown-command)))
+            (set-process-sentinel proc #'ignore)
+            (set-process-query-on-exit-flag proc nil)
+            (process-send-string proc input)
+            (process-send-eof proc))))))
     output-buffer-name))

 (defun markdown-standalone (&optional output-buffer-name)

[cruegge]

I think the synchronous version is probably better. Minor modes like markdown-preview-mode call the function and expect the result in the returned buffer for further processing, so asynchronous execution can lead to race conditions.

[jrblevin]

Thanks for reporting this. I didn't realize this was happening. I merged #86. Thanks to @syohex for the patch. Please reopen if this does not fix the issue.