[PATCH] Dired: with prefix argument, open file in new window; and question about lexical scope

[samer <samer@samertm.com>]

Hi,

In magit, <enter> opens a file in the current window, and C-u <enter> 
opens the file in a new window for the thing under the point. I think 
this is really useful pattern, and I've included a patch that brings 
this behavior to dired.

My papers haven't finished being processed, but once they are, it would 
be cool to have this merged in.

I also have a question about lexical scoping: dired.el is marked as 
lexically scoped, but you can see that it tries to pass 
`find-file-run-dired' as true to `find-file' dynamically. That has no 
effect on `find-file', right? If so, that line should be removed before 
this patch is installed.

-samer

patch:

3 files changed, 17 insertions(+), 4 deletions(-)
  etc/NEWS       |  5 +++++
  lisp/ChangeLog |  5 +++++
  lisp/dired.el  | 11 +++++++----

	Modified   etc/NEWS
diff --git a/etc/NEWS b/etc/NEWS
index 4d63278..841a982 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -224,6 +224,11 @@ typing RET.
  *** If `quick-calc' is called with a prefix argument, insert the
  result of the calculation into the current buffer.

+** Dired
+
+*** When `dired-find-file' is called with a prefix argument, the file
+under the point is opened in a new window.
+
  ** ElDoc
  *** New minor mode global-eldoc-mode
  *** eldoc-documentation-function now defaults to nil
	Modified   lisp/ChangeLog
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 5bd192d..cbcc822 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2015-01-19  Samer Masterson  <samer@samertm.com>
+
+	* dired.el (dired-find-file): Open file in other window when given
+	prefix argument.
+
  2014-12-28  Samer Masterson  <samer@samertm.com>

  	* pcomplete.el (pcomplete-parse-arguments, pcomplete-stub): Delay
	Modified   lisp/dired.el
diff --git a/lisp/dired.el b/lisp/dired.el
index 7f7251f..c936246 100644
--- a/lisp/dired.el
+++ b/lisp/dired.el
@@ -2093,13 +2093,16 @@ directory in another window."

  ;; Force C-m keybinding rather than `f' or `e' in the mode doc:
  (define-obsolete-function-alias 'dired-advertised-find-file 
'dired-find-file "23.2")
-(defun dired-find-file ()
-  "In Dired, visit the file or directory named on this line."
-  (interactive)
+(defun dired-find-file (&optional other-window)
+  "In Dired, visit the file or directory named on this line.
+With a prefix argument, visit in other window."
+  (interactive "P")
    ;; Bind `find-file-run-dired' so that the command works on 
directories
    ;; too, independent of the user's setting.
    (let ((find-file-run-dired t))
-    (find-file (dired-get-file-for-visit))))
+    (if other-window
+        (find-file-other-window (dired-get-file-for-visit))
+      (find-file (dired-get-file-for-visit)))))

  (defun dired-find-alternate-file ()
    "In Dired, visit this file or directory instead of the Dired buffer."