How can I open multiple different instances of file in Emacs? That is to say, the instances are totally independent of each other but write to the same file.
I actually want to have a reference to the original file in one buffers side-by-side with the buffer in which I will be editing while referring to the original content. I don't find opening a temporary buffer, yanking the entire original content into it and have it side-by-side, as an elegant solution.
Other solutions are welcome as well.
I have tried using clone-indirect-buffer and C-x C-v but it doesn't server the purpose.
You can create a new buffer (C-xb*new*) and insert the content of the file to it with C-xifilename.
As I read through the find-file code, I see this warning coded into it:
"The file %s is already visited normally.
You have asked to visit it literally,
meaning no coding system decoding, format conversion, or local variables.
But Emacs can only visit a file in one way at a time.
Do you want to revisit the file literally now? "
Something that would imply that Emacs' code specifically tries to protect against the situation when the same file is visited multiple times, but the buffers are out of sync with each other. However... you could open two copies of Emacs, in which case they would not know about each other visiting the same file and so would allow this situation to happen.
I can understand that the above isn't a very nice option, but it looks like adding that kind of functionality will require some time understanding the reasons behind it being specifically prevented in the first place.
I've tried this:
M-:(switch-to-buffer (find-file-noselect-1 (create-file-buffer (buffer-file-name)) (buffer-file-name) t nil (buffer-file-name) 1))
And it seems like it would work, but I'm not sure of consequences - maybe different major modes may rely on the original Emacs treatment of files and their editing history, so use with care. The last number 1 is the number to be displayed after the file name, as in Foo.bar<1> So, you'd need to change that, if you need more copies.
As mentioned, you might be able to use clone-buffer, although you'll have to let-bind buffer-file-name around the call since clone-buffer otherwise will refuse to clone it. Another option is to do:
M-x set-visited-file-name RET toto RET
C-x C-f thefile RET
C-x b RET
M-x set-visited-file-name RET thefile RET
the last set-visited-file-name should ask you if you really want to do that, but you can answer that you do and Emacs will accept your choice. Arguably, clone-buffer should not reject to do it, so you might like to submit a bug-report asking to make it behave similarly to what set-visited-file-name does.
You may have some luck with clone-buffer, depending on your mode. It has certain limitations that you can read about in the docs.
Otherwise, here's something quick and dirty:
(defun dodgy-clone-buffer ()
"Clone the current buffer. The clone will write to the original file."
(interactive)
(switch-to-buffer-other-window
(eval `(with-current-buffer
;; Create a new buffer or clear an existing one.
(get-buffer-create ,(format "*clone: %s*" (buffer-name)))
(delete-region (point-min) (point-max))
(insert ,(buffer-string))
(setq buffer-file-name ,(buffer-file-name))
(funcall ',major-mode)
(current-buffer)))))
Related
Switch-to-buffer is the function bound to C-x b. Occasionally I mistype the buffer I am intending to switch to and this causes me to open a fresh buffer with the incorrect name. The preferred behavior (in my case) is to fail to open the buffer... perhaps a failure to complete the buffer name. I recall encountering a few years back a technique that disallows switch-to-buffer to open new buffers. Perhaps someone on StackOverflow can identify that technique?
Thanks!
Setjmp
I think you want to customize confirm-nonexistent-file-or-buffer. E.g. with something like:
(setq confirm-nonexistent-file-or-buffer t)
The default is to only ask for confirmation if you've just hit completion before RET.
I was able to track down the solution in Writing GNU Emacs Extensions by Bob Glickstein. (In knew I had seen it somewhere, but it took some time to figure out where). I have the 1997 edition, and the answer is given in Chapter 2, under a section called "Advised Buffer Switching." Glickstein demonstrates the customization of switch-to-buffer as a method of instructing the reader on giving "advice" to functions.
(defadvice switch-to-buffer (before existing-buffer
activate compile)
"When interactive, switch to existing buffers only, unless given a prefix argument."
(interactive
(list (read-buffer "Switch to buffer: "
(other-buffer)
(null current-prefix-arg)))))
The function read-buffer reads the name of the buffer and returns a string. That string is passed to switch-to-buffer. The first argument is the default. The second argument is a boolean determining whether non-existing buffers are allowed.
Setjmp
I think an even better solution than preventing open a wrong buffer is switching to the buffer you meant to.
This can be done by ido.el, which is one of my favorite package. Install that package and configure as the following, then you can type much less (and ignore case) to switch to a buffer.
(ido-mode 'buffer)
(setq ido-enable-flex-matching t)
For instance, you have buffers "abcd.el", "hijk.el" "ABC.c", simply C-x b then type "a.c" and . Now, you are in "ABC.c" buffer. C-x b followed by a single character "h" will lead you to "hijk.el" buffer.
Last week, infuriated (again) by having to cope with different IDEs for R and Perl, neither of which I like or use enough to get really comfortable in, I decided to try Emacs. This decision was not made without a certain trepidation on my part. My main use is for Perl with cperl and for R with ESS. My environment is Windows 7 Ultimate 64-bit and I am running v23.4.1, which I think is what the ESS package installed on my behalf.
Nearly a week in and so far it has been surprisingly painless, no more involved than any other significant piece of software. I have remapped my ctrl key to caps-lock, changed default folders, messed around with .emacs and made some additions such as auto-install, yasnippet, color-theme, icicles and a few others. Clearly there is some very sophisticated stuff out there. In addition of course certain features of base Emacs are immediately very powerful and useful, such as isearching up and down. On the whole I have been pleasantly surprised and reassured.
One thing that is cruder than I was expecting is the process of finding and opening files. After a cursory read of various tutorials I had this image of quasi-magical file location and filename auto-completion. The main directories in my setup have paths like g:/roaming/code/perl or g:/roaming/code/R/ but I often need to branch into completely different paths like g:/pricedata/support files/sector/project01/ and so on.
Currently I laboriously delete the file path when I need to take a different fork, then use auto-complete to move deeper into that branch of the filesystem. It kinda takes me back to running a bash shell on the Amiga twenty years ago.
What had I expected? Something like (using the above example) typing 'project01' to skip immediately into the folder at the bottom of the path. For some reason I had got the idea in my head that Emacs would preload directories. So maybe this wasn't realistic.
My guess is that my difficulties probably stem from my own lack of familiarity rather than a structural shortcoming in Emacs and leads on to my questions. I can't complain that there is not enough documentation; rather there is abundant information that it is scattered around rather haphazardly. Icicles has a similar problem - if anything there's too much.
1) What is the best tactic for moving around different branches of the file tree when trying to open files in the minibuffer or using some other method? Are there aliases that can be used to shortcut from one place to another or can one specify directories to be preloaded? Do people just cd around a lot? Or am I coming at this from completely the wrong angle and need to adopt a different strategy?
2) With additional setup, can auto-complete be used to find files in (say) the project01 directly above by prefixing with wildcards etc? What should I focus on to become more efficient here? Am I not tapping the power of add-ons like icicles, anything etc?
I realise these questions veer dangerously close the deprecated category of not having clear answers. My defence is that some tips/guidance at this stage before I commit myself to bad habits or a poor long-term solution would be welcome and I suspect the answers will benefit others who might be considering the switch. I am happy to withdraw or rephrase if there are problems.
helm (formerly known as anything) might suit you. You can install it manually, or using a auto-install extension.
For the auto-install way: download it, put in Your load-path, then add to .emacs:
(add-to-list 'load-path "~/.emacs.d/site-lisp/auto-install")
(require 'auto-install)
(setq auto-install-directory "~/.emacs.d/site-lisp/auto-install/")
Then do M-x auto-install-batch anything. After that is done, put in .emacs:
(require 'anything)
(require 'anything-match-plugin)
(require 'anything-config)
(require 'anything-show-completion)
Then do M-x anything for anything.
Also give a try to ECB (stands for Emacs Code Browser). If you're on Linux, you probably have it available in a standard repository.
You could benefit from using ido-mode, which greatly enhances autocompletion nearly everywhere in emacs (especially when finding files or buffers)
(setq ido-enable-flex-matching t
ido-auto-merge-work-directories-length -1
ido-create-new-buffer 'always
ido-use-filename-at-point 'guess
ido-everywhere t
ido-default-buffer-method 'selected-window)
(ido-mode 1)
(put 'ido-exit-minibuffer 'disabled nil)
(when (require 'ido-ubiquitous nil t)
(ido-ubiquitous-mode 1))
While this might help you quickly finding files "not far away", it probably won't help you much finding files in entirely different locations.
If find that one way to begin tackling this problem is using recentf-mode to quickly jump to recent locations (if you have only a small number of usual project directories, this might do the trick). recentf can be coupled with ido using something like this (I'm not sure where I got this snippet from):
(recentf-mode 1)
(setq recentf-max-saved-items 50)
(defun ido-recentf-open ()
"Use `ido-completing-read' to \\[find-file] a recent file"
(interactive)
(if (find-file (ido-completing-read "Find recent file: " recentf-list))
(message "Opening file...")
(message "Aborting")))
(global-set-key (kbd "C-x C-r") 'ido-recentf-open)
With this, you can use C-x C-f (ido-find-file) to look for files near you current location, and C-x C-r (ido-recentf-open) to look for recently opened files (hoping one of them is not too far away from where you want to go).
There are various approaches. File name cache is a built in solution. Opening files from recent files is also very effective, especially if you set the stored files to a high number (e.g. 1000). There are also packages for opening files from anywhere on the file system. And there are meta solutions like anything.el which can show you file completions from multiple sources (history, project files, etc.) in a common interface.
You should investigate the different options to find out which is the most suitable for you.
In addition to IDO and recetf you can use the following methods:
Open the directory recursively.
(defun op-i:dired (rec)
"customized dired: will display directory recursively when called with an argument"
(interactive "P")
(let ((dir (car (find-file-read-args "Dired: " nil)))
(opts (if rec (read-string "options: " "-lhAR") "-lhA")))
(if (file-directory-p dir) (dired dir opts))))
(define-key (current-global-map) (kbd "C-x C-d") 'op-i:dired)
Then you can navigate in the directory buffer as in any other buffer using a (wildcard) search.
Use Emacs registers to point to often used directories. You can initialize them in your .emacs
(set-register ?0 (cons 'file "c:/path/to/my-project0"))
(set-register ?1 (cons 'file "c:/path/to/my-project1"))
Then jump to register using C-x r j
Other people have already mentioned anything, suffice it to say, I believe it solves all your problems. :)
Calling out one specific feature of anything is anything-locate. On *nix systems, this uses the DB created by the locate command to quickly find files. On Windows, I believe it works with "Everything", which should give you near instantaneous search results across all your files. I mean all.
Tom has mentioned file-cache. Anything works with that.
Just as a side note, Dired is an absolute monster once you get used to it. You should read the emacswiki pages related to it. In particular dired-x, which comes with Emacs binds C-x C-j, jumps to current buffer in Dired was a revelation for me. Also dired-find, wdired.
Edit: some details on why C-x C-j is awesome.
When you pop the current buffer in a Dired buffer, you can modify it, i.e. rename, delete, etc. And Emacs is aware of what you've done, and adjusts accordingly.
Other possibilities:
Bookmarks. If you use Bookmark+ then you can also:
Bookmark Dired buffers, which remembers their inserted subdirs, their markings, and their file omissions. You can have a bookmark that opens Dired to a specific set of files that need not be in the same directory or even the same directory tree.
From Dired you can hit a key to create a separate bookmark to each marked file or subdir.
Bookmark files automatically (autofiles).
Tag bookmarks and files (autofile bookmarks) with arbitrary-text tags. (Tags can even be non-text Lisp objects). Use tags to organize, search, etc. different categories of bookmarks.
Bookmark sets of bookmarks or bookmark files or Emacs desktops. Jump to such a bookmark to restore a given project state/context.
Icicles.
Define temporary or persistent sets of files on the fly, even from different directories. Operate on the files in a set in various ways. (Use Emacs filesets, less powerful, the same way.)
Complete against file names from such saved sets during any completion command, not just file-finding.
Act in different ways on candidate files during completion.
Search bookmarked objects or saved sets of files or buffers.
Dired+.
Additional navigation, including i bouncing between a subdirectory listing and the subdirectory's line in the parent listing.
Refs:
http://www.emacswiki.org/cgi-bin/wiki/BookmarkPlus
http://www.emacswiki.org/emacs/Icicles_-_Support_for_Projects
http://www.emacswiki.org/emacs/Icicles_-_File-Name_Input
http://www.emacswiki.org/cgi-bin/wiki/DiredPlus
When I start working on a project in emacs, I use M-x cd to get into the project root directory. But every time I use C-x C-f to open a file in one of the subdirectories (like app/model/Store.rb) emacs changes current directory to that of the file. Is there a way to make emacs stay at the root?
How about this? It replaces the regular find-file command with your own which always starts in some "root" directory (customize the find-file-root-dir variable):
(defvar find-file-root-dir "~/"
"Directory from which to start all find-file's")
(defun find-file-in-root ()
"Make find-file always start at some root directory."
(interactive)
(let ((default-directory find-file-root-dir))
(call-interactively 'find-file)))
(global-set-key (kbd "C-x C-f") 'find-file-in-root)
Assuming that you want the working directory of a file to be set to whatever the working directory was before you executed find-file, you could try the following:
(defmacro disallow-cd-in-function (fun)
"Prevent FUN (or any function that FUN calls) from changing directory."
`(defadvice ,fun (around dissallow-cd activate)
(let ((old-dir default-directory) ; Save old directory
(new-buf ad-do-it)) ; Capture new buffer
;; If FUN returns a buffer, operate in that buffer in addition
;; to current one.
(when (bufferp new-buf)
(set-buffer new-buf)
(setq default-directory old-dir))
;; Set default-directory in the current buffer
(setq default-directory old-dir))))
Armed with this macro, go search for operations that set the variable default-directory: M-x find-library files; M-x occur (setq default-directory. After some investigation, you discover that the desired function is called find-file-noselect-1. Also, it looks like set-visited-file-name is also a candidate. So:
(disallow-cd-in-function find-file-noselect-1)
(disallow-cd-in-function set-visited-file-name)
Note
Note that (disallow-cd-in-function find-file) would work just fine, but then if you switched to ido-mode, you'd be opening files with ido-find-file instead of find-file. Both of these functions ultimately use find-file-noselect-1, so hitting that with the macro is a more univeral solution.
Is there a way to make emacs stay at the root?
No, there isn't. C-x C-f always visits starting from the default directory of the buffer you are already vising. The default directory, by default, is the same directory as the file. You can change these (separately for every buffer) using M-x cd.
But that is not what you want. What you should do is C-x b to *scratch* (whose default directory is the same as where you launched Emacs from -- in your words "root"), and then visit a new file. And if you need to do this frequently, just open up a dired in there and work your way thru.
I appreciate I'm not answering your question directly, but I noticed you were more specific in your requirements in one of your comments: "I don't use compile or recompile, I just tend to close files I am not working on, since it takes fewer keystrokes to open a file again".
Have you got ido turned on for buffer switching? If you exclude the directory thing for a moment, switching files or buffers with ido is an identical number of keystrokes (C-x C-f vs C-x b, followed by a few characters in the file name). If you include the directory thing, switching files is more tricky for the precisely the reasons you mention. Sticking with buffers is much easier.
Going a step further, with the help of 'anything.el' it's quite easy to abstract away whether a given file is in a buffer or in a file using the file cache. For example, if you do the following:
(file-cache-add-directory-recursively "/my/ruby/project") ".*\\.rb$")
and run 'anything-for-files' (I have it bound to C-x f) all your open buffers are listed, along with all of the files you've just added to the file cache; isolating a given file usually only takes one or two more characters.
Any file in your project is thus 4 or 5 key presses away, and the directory they are in or whether or not they are in a buffer becomes irrelevant.
Hope that's helpful...
Sorry I haven't worked out the details, but you might be able to add a function to find-file-hook that resets the default directory to whatever you want.
How do I prevent Emacs from showing me all the files I'm not interested in (such as ~ backup files, .pyc files, or .orig files) when I: C-x C-f TAB ?
It is working in one respect: if I know the file I want to open begins with foo and I type foo TAB then the mini-buffer correctly autocompletes all the way to foo.py. It correctly ignored foo~ and foo.pyc, because both ~ and .pyc are in completion-ignored-extensions. It also correctly lets me open either ignored file if I really want to by typing in all the letters my self.
However, if I just hit TAB to to bring up the completion list buffer then that list includes files with extensions in completion-ignored-extensions, which makes it very difficult to find what I'm looking for.
Clearly the code to ignore uninteresting files is there and working. How do I get the completion list buffer to respect completion-ignored-extensions?
(by-the-by, can I make dired behave similarly?)
This piece of advice filters out files with extensions listed in 'completion-ignored-extensions:
(defadvice completion--file-name-table (after
ignoring-backups-f-n-completion
activate)
"Filter out results when they match `completion-ignored-extensions'."
(let ((res ad-return-value))
(if (and (listp res)
(stringp (car res))
(cdr res)) ; length > 1, don't ignore sole match
(setq ad-return-value
(completion-pcm--filename-try-filter res)))))
Note: This doesn't affect dired.
For the dired issue, add this to your .emacs
(eval-after-load "dired"
'(require 'dired-x))
(add-hook 'dired-mode-hook
(lambda ()
(dired-omit-mode 1)))
Read the documentation for dired-x to get an idea of what's available there.
I would recommend using ido-mode to ignore files; it comes with Emacs by default and adds many other useful enhancements that you'll quickly learn to love. The Ignorance is Bliss section from this Mastering Emacs blog post covers how to ignore files, directories, and buffers:
ido-ignore-buffers Takes a list of buffers to ignore in C-x b
ido-ignore-directories Takes a list of directories to ignore in C-x d and C-x C-f
ido-ignore-files Takes a list of files to ignore in C-x C-f
Icicles does what you expect by default. It always respects completion-ignored-extensions for file-name completion, including for buffer *Completions*. And you can toggle this ignoring on/off at anytime, by hitting C-. in the minibuffer.
In addition, if you use library completion-ignored-build.el by Kevin Ryde, then Icicles automatically takes advantage of that library's dynamic adjustment of ignored file extensions. (Just load completion-ignored-build.el -- do not enable its minor mode or advice.)
I don't know of an answer for completion, I'm afraid. I think this is by design - when you know the name you're looking for, you probably don't want e.g. the backup file. But when you don't know, it's probably better to have a list of all of the files.
However, for dired, you can load the 'dired-x' package on startup (in your .emacs), and this provides dired-omit-mode:
(load "dired-x")
You can use 'M-x customize-variable<RET>dired-omit-files' to set the actual patterns to ignore. Then when you are in dired mode you can use M-O (the letter, not the number) to toggle 'omission' on and off.
One problem that I have with emacs is that it doesn't seem to handle like-named files in different directories very well. For example, if I'm not careful, I'll end up with 20 __init__.py buffers open. What I've been doing is using M-x rename-buffer and renaming it to indicate what package it's within. However, doing this manually is somewhat tedious.
Does anyone have any strategies for attacking this problem?
I like uniquify, which comes with Emacs:
(require 'uniquify)
(setq uniquify-buffer-name-style 'reverse)
(setq uniquify-separator "/")
(setq uniquify-after-kill-buffer-p t) ; rename after killing uniquified
(setq uniquify-ignore-buffers-re "^\\*") ; don't muck with special buffers (or Gnus mail buffers)
With those settings, the directory gets added to the buffer name, giving you an indication of where the file is. For example, loading the files /some/path/to/Makefile and /some/path/to/different/Makefile would result in the following buffer names:
Makefile/to (which is /some/path/to/Makefile)
and
Makefile/different (which is /some/path/to/different/Makefile)
uniquify also handles updating the buffer names when buffers are deleted, so when one of the two Makefile buffers is deleted, the other gets renamed to simply Makefile.
If you want full control you can redefine create-file-buffer.
If you want the full filename it could be as simple as
(defun create-file-buffer (filename)
"Create a suitably named buffer for visiting FILENAME, and return it."
(generate-new-buffer filename))
See files.el for reference.