I've been working on an Emacs minor mode lately and part of its functionality was displaying images in separate buffers. So far I've been using a function like this:
(defun create-buffer-with-image (name)
(let ((buffer (generate-new-buffer name))
(image (get-svg-for-kanji-code name)))
(switch-to-buffer buffer)
(turn-on-iimage-mode)
(iimage-mode-buffer t)
(insert-image image)))
and it produces a buffer with the image passed as argument, but closing the buffer requires hitting C-x k and Return, which started to get cumbersome after a while. The way to simplify closing of such transient buffers would be to have a key binding for the kill-this-buffer function, but it would need to be buffer-specific, so as not to mess up anything else. The question is how to make such a binding with the creation of a buffer.
From EmacsWiki: https://www.emacswiki.org/emacs/BufferLocalKeys
For buffer-local keys, you cannot use local-set-key, unless you want to modify the keymap of the entire major-mode in question: local-set-key is local to a major-mode, not to a buffer.
For buffer-local modifications, use this instead:
(use-local-map (copy-keymap foo-mode-map))
(local-set-key "d" 'some-function)
Written by: TiagoSaboga
To inspect the change, type C-h b aka M-x describe-bindings
I'd suggest you add a call to special-mode after the call to switch-to-buffer.
In the longer run, you'll want to use your own major mode, so you'd do:
(define-derived-mode my-image-mode special-mode "MyImage"
"My own major mode to display images."
;; We could add more things here
)
(defun create-buffer-with-image (name)
(with-current-buffer (generate-new-buffer name)
(my-image-mode)
(let ((image (get-svg-for-kanji-code name)))
(turn-on-iimage-mode)
(iimage-mode-buffer t)
(insert-image image)
(pop-to-bffer (current-buffer)))))
I was a bit mislead by some posts on the web suggesting the use of local-key-binding, but somehow it did not work for me - when the image was displayed and I examined the key bindings, my choice of q was not in effect. After some experimentation and digging through elisp references I found that I needed to use local-set-key. So now my function looks like this:
(defun create-buffer-with-image (name)
(let ((buffer (generate-new-buffer name))
(image (get-svg-for-kanji-code name)))
(switch-to-buffer buffer)
(local-set-key (kbd "q") 'kill-this-buffer)
(turn-on-iimage-mode)
(iimage-mode-buffer t)
(insert-image image)))
and the newly created image buffer can easily be closed by pressing q.
Create a minor mode:
(define-minor-mode my-mode "my doc" nil nil (make-sparse-keymap))
Then you can use this mode's my-mode-map to define your keybindings. Activate the mode with (my-mode).
Related
I'm trying to write a custom tab completion implementation which tries a bunch of different completions depending on where the point is. However, if none of the conditions for completions are met I would like tab to do what ever the current mode originally intended it to do.
Something like this:
(defun my-custom-tab-completion ()
(interactive)
(cond
(some-condition
(do-something))
(some-other-condition
(do-something-else))
(t
(do-whatever-tab-is-supposed-to-do-in-the-current-mode))) ;; How do I do this?
Currently I'm checking for specific modes and doing the right thing for that mode, but I really would like a solution that just does the right thing without me having to explicitly add a condition for that specific mode.
Any ideas of how to do this?
Thanks! /Erik
BTW, here is another solution:
(define-key <map> <key>
`(menu-item "" <my-cmd> :filter ,(lambda (cmd) (if <my-predicate> cmd))))
Here is a macro I wrote based on Emacs key binding fallback to define a keybinding conditionally. It adds the keybinding to the specified minor mode but if the condition is not true, the previously assigned action is executed:
(defmacro define-key-with-fallback (keymap key def condition &optional mode)
"Define key with fallback. Binds KEY to definition DEF in keymap KEYMAP,
the binding is active when the CONDITION is true. Otherwise turns MODE off
and re-enables previous definition for KEY. If MODE is nil, tries to recover
it by stripping off \"-map\" from KEYMAP name."
`(define-key ,keymap ,key
(lambda () (interactive)
(if ,condition ,def
(let* ((,(if mode mode
(let* ((keymap-str (symbol-name keymap))
(mode-name-end (- (string-width keymap-str) 4)))
(if (string= "-map" (substring keymap-str mode-name-end))
(intern (substring keymap-str 0 mode-name-end))
(error "Could not deduce mode name from keymap name (\"-map\" missing?)"))))
nil)
(original-func (key-binding ,key)))
(call-interactively original-func))))))
Then I can do things like the following to use the special binding for TAB only when I am on a header in outline-minor-mode. Otherwise my default action (I have both indent and yasnippets) is executed:
(define-key-with-fallback outline-minor-mode-map (kbd "TAB")
(outline-cycle 1) (outline-on-heading-p))
You could use functions such as key-binding (or its more specific variants global-key-binding, minor-mode-key-binding and local-key-binding) to probe active keymaps for bindings.
For example:
(call-interactively (key-binding (kbd "TAB")))
;; in an emacs-lisp-mode buffer:
;; --> indent-for-tab-command
;;
;; in a c++-mode buffer with yas/minor-mode:
;; --> yas/expand
One way to avoid infinite loops if your command is bound to TAB could be to put your binding in a minor mode, and temporarily disable its keymap while looking for the TAB binding:
(define-minor-mode my-complete-mode
"Smart completion"
:keymap (let ((map (make-sparse-keymap)))
(define-key map (kbd "TAB") 'my-complete)
map))
(defun my-complete ()
(interactive)
(if (my-condition)
(message "my-complete")
(let ((my-complete-mode nil))
(call-interactively (key-binding (kbd "TAB"))))))
It's possible that you could achieve this without any special workarounds at all. In most modes TAB just does indentation by default, but if you set the global variable tab-always-indent to 'complete it will try to do completion first, and indent if no completion is possible. This usually works really well, although if TAB is bound to another command in one of your major modes you might be out of luck.
If that works in the modes you need, you'll just need to add your custom completion function to the front of the list completion-at-point-functions in all applicable buffers (maybe using a mode hook). The completion-at-point command calls each function listed in completion-at-point-functions until one of them returns non-nil, so all you need to do to have your custom completion function "fall through" to the existing behavior is return nil from it.
This isn't a 100% answer to the question, but if the major modes you're working with are written according to the normal guidelines it might be the cleanest way.
define-key can accept quoted string or interactive lambdas like in this example.
;Static
(define-key evil-normal-state-mapr "m" 'evil-motion-state)
;Conditional
(define-key evil-normal-state-map "m"
(lambda () (interactive) (message "%s" major-mode)))
Lambda's can be replaced with named functions like my-tab-completion and used more effectively.
From define-key's docstring (Emacs 25)
DEF is anything that can be a key's definition:
nil (means key is undefined in this keymap),
a command (a Lisp function suitable for interactive calling),
a string (treated as a keyboard macro),
a keymap (to define a prefix key),
a symbol (when the key is looked up, the symbol will stand for its
function definition, which should at that time be one of the above,
or another symbol whose function definition is used, etc.),
a cons (STRING . DEFN), meaning that DEFN is the definition
(DEFN should be a valid definition in its own right),
or a cons (MAP . CHAR), meaning use definition of CHAR in keymap MAP,
or an extended menu item definition.
(See info node `(elisp)Extended Menu Items'.)
Once in a while I manually set the font-family and size different from the default, and I use buffer-face-mode to do it. (To be exact I use the mouse & pick one from the dialog box.) Once I set it, I'd like it to stay set for that buffer, even if I change modes, so I tried a customization. The idea was to add a change-major-mode-hook (which runs just before buffer-locals get killed) that would save the buffer face, if it is set, in a function to be called later- that much seems to work. But then that function seems to be called too soon, and when the mode change is over, buffer-face-mode is not active.
Here's the customization I cam up with so far
(defun my-preserve-bufface-cmmh ()
"Keep the state of buffer-face-mode between major-mode changes"
(if (and (local-variable-p 'buffer-face-mode) buffer-face-mode)
(delay-mode-hooks
(message "face is %s" buffer-face-mode-face) ; Just to show me it has the right face
(let ((my-inner-face buffer-face-mode-face))
(run-mode-hooks
(message "inner %s" my-inner-face) ; it still has the right face here
(setq buffer-face-mode-face my-inner-face)
(buffer-face-mode))))))
(add-hook 'change-major-mode-hook
'my-preserve-bufface-cmmh)
The messages both run and show a custom face, as they should, when I'm changing major-mode in a buffer with the minor-mode buffer-face-mode set. I had thought the combination of delay-mode-hooks ... run-mode-hooks would make setq buffer-face-mode-face ... (buffer-face-mode) run after the new mode was set up, but apparently not.
Is this customization "close"/salvageable for my wants? Is there a cleaner way?
The first thing is that delayed-mode-hooks is itself a local variable.
That means, if you set it by (delay-mode-hooks (run-mode-hooks ...)) in change-major-mode-hook
this will have no effect since it is killed instantaneously.
The second thing is that the stuff within your run-mode-hooks is
evaluated within my-preserve-bufface-cmmh. It should be defined as a back-quoted hook function
`(lambda () ...) where you splice in the values you want to keep.
The alternative would be to use lexical binding (which google).
The 2nd thing is demonstrated in the following example (to be evaluated step-by-step):
(defun test (str)
(let ((mytest (concat "hello " str)))
(add-hook 'my-own-hook `(lambda () (message "mytest:%S" ,mytest)))))
(test "you")
(run-hooks 'my-own-hook)
(test "world")
(run-hooks 'my-own-hook)
(put :myface 'test)
If you want to keep the font buffer-local you have to use a local variable that survives kill-all-local-variables such as buffer-file-name. You can hook a property there:
Edit: Even if the symbol has a buffer local value its properties are not buffer local. Thus, the previous approach did not work. Better: Create your own permanent buffer-local variable:
(defvar-local my-preserve-bufface nil
"Keep the state of buffer-face-mode between major-mode changes")
(put 'my-preserve-bufface 'permanent-local t)
(defun my-preserve-bufface-put ()
"Keep the state of buffer-face-mode between major-mode changes"
(and (local-variable-p 'buffer-face-mode)
buffer-face-mode
(setq my-preserve-bufface buffer-face-mode-face)))
(defun my-preserve-bufface-get ()
"Keep the state of buffer-face-mode between major-mode changes"
(and my-preserve-bufface
(setq buffer-face-mode-face my-preserve-bufface)
(buffer-face-mode)))
(add-hook 'change-major-mode-hook 'my-preserve-bufface-put)
(add-hook 'after-change-major-mode-hook 'my-preserve-bufface-get)
Thanks for the educational comments and especially the answer/example from #user2708138, which I am going to accept because it does answer the question.
Yet I am also going to answer my own question, since I did come up with working code that is a more general solution. I went down this path after finding I also wanted my font-size changes maintained and that they were from text-scale-mode, one more minor-mode to keep. This code reads a list of minor-modes to preserve, without my having to figure out which variables they use. (It isn't too hard for a human to figure them out, but I wanted to try having emacs do it).
Alas there is no function I know of to retrieve the variables used by a minor-mode, but the modes I'm interested in use the convention minor-mode-var-name, so this code just filters buffer-local variables for that pattern.
; Save & restore minor modes I wish to be "permanent" if set
(setq my-preserve-minor-modes '(buffer-face-mode text-scale-mode))
(defun my-preserve-minor-modes-cmmh ()
"Keep the state of desired-permanent minor modes between major-mode changes. Assumes that associated buffer-local minor-mode variables to save begin with `minor-mode-'"
(setq my-restore-minor-modes-acmmh nil)
(dolist (mm my-preserve-minor-modes)
(when (and (local-variable-p mm) (symbol-value mm))
(push mm my-restore-minor-modes-acmmh)))
(when my-restore-minor-modes-acmmh
(add-hook 'after-change-major-mode-hook 'my-restore-minor-modes-acmmh)
; Predicate-list showing if symbol starts with a preserved mode
(let ((mm-p-l `(lambda (locvar-nm)
(or ,#(mapcar (lambda (mm)
`(and (< ,(length (symbol-name mm))
(length locvar-nm))
(string-prefix-p ,(symbol-name mm)
locvar-nm)))
my-restore-minor-modes-acmmh)))))
; For each found minor mode, create fn to restore its buf-local variables
(dolist (locvar (buffer-local-variables))
(if (and (listp locvar) (funcall mm-p-l (symbol-name (car locvar))))
(push `(lambda()(setq ,(car locvar) ',(cdr locvar)))
my-restore-minor-modes-acmmh))))))
(defun my-restore-minor-modes-acmmh ()
"After major-mode change, restore minor-mode state, and remove self from hook. It restores state by calling the function stored in the variable my-restore-minor-modes-acmmh."
(remove-hook 'after-change-major-mode-hook 'my-restore-minor-modes-acmmh)
(dolist (restore-f my-restore-minor-modes-acmmh) (funcall restore-f)))
(add-hook 'change-major-mode-hook 'my-preserve-minor-modes-cmmh)
I did know about the permanent-local property but I wasn't sure about any unwanted side-effects... probably unwarranted paranoia on my part!
My answer could be improved if there is ever a way to get a list of variables for a minor mode, or by having the user specify an alist of variables per minor mode- in either case we wouldn't have to loop over buffer-local-variables anymore, and maybe simply making those all permanent-local would be all we need, simplifying the code quite a bit. Anyway, figuring all this out (with your help & looking at the fine manual) was quite educational.
Context: I want to make a minor mode where pressing f twice fast results in whatever the pressing of ( should do at that time. This doesn't always mean just insertion of (. For example, in buffers where paredit mode or autopair mode is enabled, pressing of ( usually results in insertion of (). In a paredit mode buffer, that sometimes results in wrapping the selected text: for example, if I select a b and press (, that should result in replacing the selection with (a b).
For detection of f being pressed twice, I just need to take the logic in the short code in http://www.emacswiki.org/emacs/electric-dot-and-dash.el
So the only missing piece is a Lisp code snippet that tells Emacs "Trigger pressing of ( now!"
The first thing that came to my mind was that the snippet should do
find the command bound to the key (
and then call call-interactively on that command.
but that breaks down if the auto pairing package (autopair or paredit or other similar package) binds ( to a command that has a logic that looks up what key was used to call the command, or if the package simply relies on post-self-insert-hook or post-command-hook instead of binding (.
update
I've looked up Key Chord documentation and it turns out what I am trying to do with answers to this question has a simpler solution:
(require 'key-chord)
(key-chord-mode 1)
(defvar my-easy-open-paren-mode-map
(let ((map (make-sparse-keymap)))
(key-chord-define map ",." (kbd "("))
map))
(define-minor-mode my-easy-open-paren-mode
"In this mode, pressing . and , together is another way of pressing the open paren.")
(defvar my-easy-semicolon-mode-map
(let ((map (make-sparse-keymap)))
(key-chord-define map ";;" (kbd "C-e ;"))
map))
(define-minor-mode my-easy-semicolon-mode
"In this mode, pressing semicolon twice fast is another way of pressing C-e and semicolon.")
(add-hook 'prog-mode-hook 'my-easy-open-paren-mode)
(add-hook 'c-mode-common-hook 'my-easy-semicolon-mode)
Triggering key press may still be useful in other contexts though.
You might appreciate the Key Chord library for binding functions to a double key-press. (I wouldn't recommend using f if you'll be writing in English, mind you; but YMMV.)
post-self-insert-hook would still run if the binding was self-insert-command. post-command-hook will run in any case, but if you're worried about it seeing an incorrect function and/or input event, you can manipulate those...
After looking up the binding, your function can set this-command to the function you're about to call-interactively, and last-command-event to the required key. e.g.:
(defun my-fake-paren ()
(interactive)
(let ((command (key-binding "(")))
(setq last-command-event ?\()
(setq this-command command)
(call-interactively command)))
I use Key Chord for this sort of thing, although the page you link appears to do the same thing. The trick is getting the call to call-interactively to work correctly. I wrapped it in a let that reset the variable last-command-event, such that call-interactively thinks it was a "(". This works for me in paredit and fundamental modes.
(require 'key-chord)
(key-chord-mode 1)
(defun my-paren-call ()
(interactive)
(let ((last-command-event ?\())
(call-interactively (key-binding "("))))
(key-chord-define-global "ff" 'my-paren-call)
I'm trying to write a custom tab completion implementation which tries a bunch of different completions depending on where the point is. However, if none of the conditions for completions are met I would like tab to do what ever the current mode originally intended it to do.
Something like this:
(defun my-custom-tab-completion ()
(interactive)
(cond
(some-condition
(do-something))
(some-other-condition
(do-something-else))
(t
(do-whatever-tab-is-supposed-to-do-in-the-current-mode))) ;; How do I do this?
Currently I'm checking for specific modes and doing the right thing for that mode, but I really would like a solution that just does the right thing without me having to explicitly add a condition for that specific mode.
Any ideas of how to do this?
Thanks! /Erik
BTW, here is another solution:
(define-key <map> <key>
`(menu-item "" <my-cmd> :filter ,(lambda (cmd) (if <my-predicate> cmd))))
Here is a macro I wrote based on Emacs key binding fallback to define a keybinding conditionally. It adds the keybinding to the specified minor mode but if the condition is not true, the previously assigned action is executed:
(defmacro define-key-with-fallback (keymap key def condition &optional mode)
"Define key with fallback. Binds KEY to definition DEF in keymap KEYMAP,
the binding is active when the CONDITION is true. Otherwise turns MODE off
and re-enables previous definition for KEY. If MODE is nil, tries to recover
it by stripping off \"-map\" from KEYMAP name."
`(define-key ,keymap ,key
(lambda () (interactive)
(if ,condition ,def
(let* ((,(if mode mode
(let* ((keymap-str (symbol-name keymap))
(mode-name-end (- (string-width keymap-str) 4)))
(if (string= "-map" (substring keymap-str mode-name-end))
(intern (substring keymap-str 0 mode-name-end))
(error "Could not deduce mode name from keymap name (\"-map\" missing?)"))))
nil)
(original-func (key-binding ,key)))
(call-interactively original-func))))))
Then I can do things like the following to use the special binding for TAB only when I am on a header in outline-minor-mode. Otherwise my default action (I have both indent and yasnippets) is executed:
(define-key-with-fallback outline-minor-mode-map (kbd "TAB")
(outline-cycle 1) (outline-on-heading-p))
You could use functions such as key-binding (or its more specific variants global-key-binding, minor-mode-key-binding and local-key-binding) to probe active keymaps for bindings.
For example:
(call-interactively (key-binding (kbd "TAB")))
;; in an emacs-lisp-mode buffer:
;; --> indent-for-tab-command
;;
;; in a c++-mode buffer with yas/minor-mode:
;; --> yas/expand
One way to avoid infinite loops if your command is bound to TAB could be to put your binding in a minor mode, and temporarily disable its keymap while looking for the TAB binding:
(define-minor-mode my-complete-mode
"Smart completion"
:keymap (let ((map (make-sparse-keymap)))
(define-key map (kbd "TAB") 'my-complete)
map))
(defun my-complete ()
(interactive)
(if (my-condition)
(message "my-complete")
(let ((my-complete-mode nil))
(call-interactively (key-binding (kbd "TAB"))))))
It's possible that you could achieve this without any special workarounds at all. In most modes TAB just does indentation by default, but if you set the global variable tab-always-indent to 'complete it will try to do completion first, and indent if no completion is possible. This usually works really well, although if TAB is bound to another command in one of your major modes you might be out of luck.
If that works in the modes you need, you'll just need to add your custom completion function to the front of the list completion-at-point-functions in all applicable buffers (maybe using a mode hook). The completion-at-point command calls each function listed in completion-at-point-functions until one of them returns non-nil, so all you need to do to have your custom completion function "fall through" to the existing behavior is return nil from it.
This isn't a 100% answer to the question, but if the major modes you're working with are written according to the normal guidelines it might be the cleanest way.
define-key can accept quoted string or interactive lambdas like in this example.
;Static
(define-key evil-normal-state-mapr "m" 'evil-motion-state)
;Conditional
(define-key evil-normal-state-map "m"
(lambda () (interactive) (message "%s" major-mode)))
Lambda's can be replaced with named functions like my-tab-completion and used more effectively.
From define-key's docstring (Emacs 25)
DEF is anything that can be a key's definition:
nil (means key is undefined in this keymap),
a command (a Lisp function suitable for interactive calling),
a string (treated as a keyboard macro),
a keymap (to define a prefix key),
a symbol (when the key is looked up, the symbol will stand for its
function definition, which should at that time be one of the above,
or another symbol whose function definition is used, etc.),
a cons (STRING . DEFN), meaning that DEFN is the definition
(DEFN should be a valid definition in its own right),
or a cons (MAP . CHAR), meaning use definition of CHAR in keymap MAP,
or an extended menu item definition.
(See info node `(elisp)Extended Menu Items'.)
How to kill the buffer in emacs without being questioned.
This will kill the current visible buffer without confirmation unless the buffer has been modified. In this last case, you have to answer y/n.
(global-set-key [(control x) (k)] 'kill-this-buffer)
I use this
(defun volatile-kill-buffer ()
"Kill current buffer unconditionally."
(interactive)
(let ((buffer-modified-p nil))
(kill-buffer (current-buffer))))
(global-set-key (kbd "C-x k") 'volatile-kill-buffer) ;; Unconditionally kill unmodified buffers.
It will kill the buffer unless it's modified.
OK, I've done some poking around in the Emacs manual and found a working solution (as of Emacs 23.4.1). It's almost identical to Noufal's solution:
(defun kill-this-buffer-volatile ()
"Kill current buffer, even if it has been modified."
(interactive)
(set-buffer-modified-p nil)
(kill-this-buffer))
I've renamed the function a bit to make it a closer cousin to kill-this-buffer.
Apparently, the EmacsWiki has a page on this topic at http://www.emacswiki.org/emacs/KillBufferUnconditionally (modified in 2007), but the code is just a copy of Noufal's.
Use (kill-current-buffer) instead of (kill-this-buffer) if you want to bind it to some key. See the docs for (kill-this-buffer)
...
This command can be reliably invoked only from the menu bar,
otherwise it could decide to silently do nothing.
and (kill-current-buffer)
...
This is like ‘kill-this-buffer’, but it doesn’t have to be invoked
via the menu bar, and pays no attention to the menu-bar’s frame.
So I would put the following in my init.el:
(global-set-key (kbd "C-x k") 'kill-current-buffer)
This works at least in emacs 26.1.
I use the following piece of code -- unlike Noufal's solution of ignoring the buffer being modified or not, this will save the buffer and then kill it. It also deletes the window which makes a difference when you have several sub-windows showing -- by default it will remove the window instead of switching to some other buffer. (To use this conveniently, you need to bind some key to it, of course.)
;; Kill the current buffer immediatly, saving it if needed.
(defvar kill-save-buffer-delete-windows t
"*Delete windows when `kill-save-buffer' is used.
If this is non-nil, then `kill-save-buffer' will also delete the corresponding
windows. This is inverted by `kill-save-buffer' when called with a prefix.")
(defun kill-save-buffer (arg)
"Save the current buffer (if needed) and then kill it.
Also, delete its windows according to `kill-save-buffer-delete-windows'.
A prefix argument ARG reverses this behavior."
(interactive "P")
(let ((del kill-save-buffer-delete-windows))
(when arg (setq del (not del)))
(when (and (buffer-file-name) (not (file-directory-p (buffer-file-name))))
(save-buffer))
(let ((buf (current-buffer)))
(when del (delete-windows-on buf))
(kill-buffer buf))))