Wednesday, June 24, 2009

Emacs Tip #31: kill-other-buffers-of-this-file-name

A friend mentioned he wanted a way to get rid of all the other buffers visiting files that of the same file name. I instantly realized this was something I'd wanted for a long time without knowing it.

My usage is that I'm often viewing different versions of the same file, usually in different sandboxes. And, I might also have older versions checked out, whose file names are the same, but end with ".~1.12~" (or whatever version number was checked out).

I'm still old-school and don't use anything fancy for my buffer switching like `ido` or `icicles` or `iswitchb` or any of the other myriad of choices. And, as a result, it's a pain to switch because I have to now discern between the variants. Well, do that once, type `C-x K`, and that'll be the only buffer left for that file name.

(global-set-key (kbd "C-x K") 'kill-other-buffers-of-this-file-name)
(defun kill-other-buffers-of-this-file-name (&optional buffer)
"Kill all other buffers visiting files of the same base name."
(interactive "bBuffer to make unique: ")
(setq buffer (if buffer (get-buffer buffer) (current-buffer)))
(cond ((buffer-file-name buffer)
(let ((name (file-name-nondirectory (buffer-file-name buffer))))
(loop for ob in (buffer-list)
do (if (and (not (eq ob buffer))
(buffer-file-name ob)
(let ((ob-file-name (file-name-nondirectory (buffer-file-name ob))))
(or (equal ob-file-name name)
(string-match (concat name "\\(\\.~.*\\)?~$") ob-file-name))) )
(kill-buffer ob)))))
((message "This buffer has no file name."))))

Edited Sept. 30, 2009 to fix coding error.

Friday, June 19, 2009

Searching GNU From Firefox

When writing up answers for Emacs related questions on, I like to include links to the info pages. I got tired of having to go to the gnu site and then do a google site-specific search. I tried looking for a Firefox search plugin that already did that (or something similar), but to no avail.

However, it's pretty easy to write the search plugin yourself. The main page for creating search plugins on mozilla's developer site gives you pretty much all you need to know, except for where to put the xml file. This page shows you that the installation dir is very likely C:\Program Files\Mozilla Firefox\searchplugins.

You can read the documentation yourself, or just check out the snippet of XML I wrote.

Probably the "hardest" part was finding an icon, and the all-knowing google led me to the web page, where someone had drawn the standard GNU icon and made it available under a Creative Commons license:

Friday, June 12, 2009

Emacs Tip #30: igrep

Finding text in files is an everyday (every hour) occurrence for most programmers. And in Unix-land, people generally use grep to do the searching.

Of course Emacs has an interface to grep, which now (as of Emacs 22) even has interfaces for using both find and grep together to search through directory structures (grep-find, rgrep).

But, before those existed, someone wrote a nice package igrep.el, which has a very intuitive (IMO) interface.

M-x igrep-find RET RET /search/in/here/*.cxx RET

which will search for regexp in all the files with the extension .cxx underneath the /search/in/here/ directory.

As you'd expect, the results of the search show up in a buffer, and clicking on any one of them jumps you to that spot in the file. And the standard M-x next-error (aka C-x `) will jump you to the next match.

About the only thing I don't like is that the paths returned in the results are the fully expanded path. In other words, when the paths to the files are really long, most of the result buffer is taken up with just the pathname. So I wrote this little snippet of code which post-processes the buffer to trim the names relative to the search path entered (in the example above, all the /search/in/here/ would be removed from the file names.

(defun my-shorten-filenames-in-compilation (buffer &optional stat)
"remove the absolute filenames if they match the default-directory"
(interactive "b")
(set-buffer buffer)
(goto-char (point-min))
(let ((buffer-read-only nil)
(base-dir (if (re-search-forward "find \\([^ ]+\\) " nil t)
(if (string-match "/$" (match-string 1))
(match-string 1)
(concat (match-string 1) "/"))
(setq default-directory base-dir)
(while (re-search-forward (concat "^" default-directory) nil t)
(replace-match "")))))

(add-hook 'compilation-finish-functions 'my-shorten-filenames-in-compilation)

I do realize that the built-in M-x rgrep does this automatically, I just prefer the igrep interface.