Infinite loop when byte compile - emacs

I'm author of evil-commentary, the full source less than 200 lines can be found in the repo.
Basically I have something like this.
(evil-define-operator evil-commentary (beg end type)
"Comment or uncomment region that {motion} moves over."
:move-point nil
(interactive "<R>")
(let ((comment-function
(cdr (assoc major-mode
evil-commentary-comment-function-for-mode-alist))))
(if comment-function (funcall comment-function beg end)
(comment-or-uncomment-region beg end))))
(defun evil-commentary-comment-for-org (beg end)
"Comment function for `org-mode'."
(interactive "r")
(if (and (fboundp 'org-in-src-block-p)
(org-in-src-block-p))
(evil-commentary-do-in-org-src-block beg end
(call-interactively 'evil-commentary))
(comment-or-uncomment-region beg end)))
The idea is that evil-commentary will call evil-commentary-comment-for-org in an org file, and if we're in a src block, evil-commentary-comment-for-org will call evil-commentary again in the src-edit buffer (which now has different major-mode)
The setup works just fine, however when I compile the code, I get an infinite loop evil-commentary -> evil-commentary-comment-for-org -> evil-commentary... with Variable binding depth exceeds max-specpdl-size error...
I found that it will work if I compile the code after org is loaded, but that not I wanted because evil-commentary will stop working if an user compile with an old version of org then upgrade it. (A flaw of package.el)
Thank you!

The problem is in this line, which expands to:
(org-babel-do-in-edit-buffer
(call-interactively 'evil-commentary))
If you haven't loaded org, the byte compiler doesn't know org-babel-do-in-edit-buffer is a macro, and can't expand it. So it simply compiles a call to an (as of yet unknown) function called org-babel-do-in-edit-buffer.
When execution reaches that line, the function arguments are evaluated first (as in any other function call) and there you have your infinite loop.
Try requiring org inside an eval-when-compile block.

Related

How to rewrite a native defun in Emacs?

Premises:
My Emacs has a small bug (cannot go up from inside of "") in one of its original defun (up-list). This defun is vital to one of my frequently used command (backward-up-list) which is bound to C-M-u.
Therefore, I wanted to achieve below objectives:
Write a NEW defun named my-up-list which has the bug fix;
RE-write the native defun backward-up-list to call the above new defun (instead of the native buggy up-list). (By RE-writing under the same defun name, I intend to preserve its original convenient key bindings.)
By following the Emacs Tutorial Here, I implemented it as below:
I wrote a new defun my-up-list inside .emacs file; (see code in the end)
I rewrote the defun backward-up-list under a the same name inside .emacs file; (see code in the end).
However, when wI tested it out by trying it in "|" (| is the cursor position), I encounter below error:
backward-up-list: Wrong number of arguments: (lambda nil (interactive) (let ((s (syntax-ppss))) (if (nth 3 s) (progn (goto-char (nth 8 s))))) (condition-case nil (progn (up-list)) (error nil))), 1 [2 times]
Question:
Is it the correct way to re-write a native defun just by putting the
new implementation with the same name in .emacs file?
What may went wrong in my code?
Reference:
(The my-up-list is from here)
;; I only changed "up-list" to "my-up-list" -modeller
(defun backward-up-list (&optional arg)
"Move backward out of one level of parentheses.
With ARG, do this that many times.
A negative argument means move forward but still to a less deep spot.
This command assumes point is not in a string or comment."
(interactive "^p")
(my-up-list (- (or arg 1))))
;; copied from solution to another question - modeller
(defun my-up-list ()
(interactive)
(let ((s (syntax-ppss)))
(when (nth 3 s)
(goto-char (nth 8 s))))
(ignore-errors (up-list)))
I guess your my-up-list function needs to accept the same arguments as the original up-list, and call up-list with them?
The simplest way to do this is with the "advice" system. This provides some simple ways to wrap and extend existing functions. There's a whole section in the elisp manual explaining how to do it.

Duplicating a line in emacs with Ace-Jump

I'm fairly new to elisp, but one thing that I really want to figure out is either how to wait for ace-jump to end before executing instructions or how get a position from ace-jump instead of moving my cursor. My goal is to be able to select a line with ace-jump, copy it, then paste it right above my current line. I started by first trying to go to a line with ace-jump then duplicate it in place, but that hasn't worked. Here is what I have for that:
(defun ace-jump-yank-line-above ()
(interactive)
(ace-jump-line-mode)
(kill-ring-save (line-beginning-position) (line-beginning-position 2) )
(yank)
)
But this gives me strange behavior
You can have a look at the source of my project lispy.el.
It's got several functions that use ace-jump-mode and do something after.
For instance lispy-ace-symbol will ace-jump to symbol and mark it.
Here's the implementation detail - the key is setting ace-jump-mode-hook:
(defun lispy--ace-do (x bnd &optional filter func no-narrow)
"Use `ace-jump-do' to X within BND when FILTER return t.
When FUNC is not nil, call it after a successful move.
When NO-NARROW is not nil, don't narrow to BND."
(require 'ace-jump-mode)
(lispy--recenter-bounds bnd)
(unless no-narrow
(narrow-to-region (car bnd) (cdr bnd)))
(when func
(setq ace-jump-mode-end-hook
(list `(lambda()
(setq ace-jump-mode-end-hook)
(,func)))))
(let ((ace-jump-mode-scope 'window)
(ace-jump-search-filter filter))
(ace-jump-do x))
(widen))
I use something similar to ace-jump rather than ace-jump itself, but something like this should work (can't be sure about the call to ace-jump-line-mode):
(defun ace-jump-yank-line-above ()
(interactive)
(let ((loc (point-at-bol))
(line nil))
(save-excursion
(ace-jump-line-mode)
(setq line (buffer-substring-no-properties
(point-at-bol) (point-at-eol)))
(goto-char (1- loc))
(if (bobp)
(insert (concat line "\n"))
(insert (concat "\n" line))))))
Okay, none of these worked for me, but I used these answers to create a script that works. Here is the code that I used:
;; The base function for the line-based ones
(defun ace-jump-end-do (dfunc afunc)
;; Save where to return to as a marker
(setq ace-jump-do-retpos (make-marker))
(set-marker ace-jump-do-retpos (point))
;; Add our during function to the hook
(setq ace-jump-mode-end-hook
(list `(lambda()
(progn
(setq ace-jump-mode-end-hook)
(,dfunc)
(goto-char ace-jump-do-retpos)
(set-marker ace-jump-do-retpos nil)
(,afunc)
))))
(ace-jump-line-mode)
)
;; Copy the line above the current line
(defun ace-jump-yank-line-above ()
(interactive)
(ace-jump-end-do
;; At the line
(lambda ()
;; Store the line in a variable
(setq line (buffer-substring-no-properties (point-at-bol) (point-at-eol)))
)
;; Upon returning
(lambda ()
(save-excursion
(goto-char (point-at-bol))
(insert (concat line "\n"))
)
(when (bolp) (goto-char (point-at-bol 2)))
)))
Unfortunately, this resets the end hook of ace-jump every time it's called. It works for me though since I don't have anything else hooked to it. If I run into issues, I'll need to figure something else out.
ace-jump-mode is really silly... calling it just goes into some useless minor-mode where you pick the hints, but it is non-blocking: any code afterwards is executed immediately.
There is so much potential for this kind of interaction and ace-jump-mode completely wastes it away with crazy implementation. It also doesn't work at all with save-excursion and you wound need to hack around that with various hooks and state-saving variables.
I've written a new package addressing all these issues, you can find it at https://github.com/Fuco1/better-jump Hopefully people will pick it up, but it serves me well at least. Took me about 2 hours to write the basic working prototype and it already covers all the functionality of packages like ace-link, ace-window and ace-whatever-else-you-can-find (also ace-jump, obviously :))

AUCTeX: Run Compile Command n-times

I'd like to have a function that asks for a number n and executes the default compile command n-times afterwards. That is to say unlike C-c C-c (i.e. TeX-command-master) I don't want to be asked which command to run, it should select the default compile command based on the AUCTeX settings. Naturally if any error occurs the execution should stop.
I know about TeX-texify, however, this doesn't statisfy my needs because sometimes I just want emacs to run pdflatex five times indepent of what the AUCTeX parser thinks is adequate.
Any help is much appreciated!
Edit: I have looked into this a little further and using code from the above reference I have started writing a function that does this. However, it has one major flaw. Let me first give you the code:
(defcustom TeX-MultiTeX-Command "LaTeX" "Default MultiTeX command" :type 'string :group 'TeX-command)
(defun TeX-MultiTeX (n)
"Run TeX-command n-times"
(interactive "nRun TeX/LaTeX how many times: ")
(while (> n 0)
(TeX-command TeX-MultiTeX-Command 'TeX-master-file)
(setq n (- n 1))))
As you can see, I have implemented a config variable for selecting the correct compilation command. Now let me present the problem:
The compilation of the LaTeX document takes some time, however, my function instantly calls the second (and following) executions of the compile command. Maybe someone can provide help in finding a solution that checks whether compilation has finished successfully prior to executing (TeX-command TeX-MultiTeX-Command 'TeX-master-file), then executes said function or prints some error message if compilation finished with an error.
With the help of the code of the TeX-texify function I have developed a function that does what I want, the code is given below.
I'd like to thank user4815162342; although this solution is not based on his suggestion, I think his solution might be of use for a different problem. Also I'd like to thank TN, the author of TeX-texify, I shamelessly took and adapted his code for my problem. ;)
(defcustom TeX-MultiTeX-Command "LaTeX"
"Default MultiTeX command"
:type 'string :group 'TeX-command)
(defun TeX-MultiTeX-sentinel (&optional proc sentinel)
"Non-interactive! Call the standard-sentinel of the current LaTeX-process.
If there is still something left do do start the next latex-command."
(set-buffer (process-buffer proc))
(funcall TeX-MultiTeX-sentinel proc sentinel)
(let ((case-fold-search nil))
(when (string-match "\\(finished\\|exited\\)" sentinel)
(set-buffer TeX-command-buffer)
(unless (plist-get TeX-error-report-switches (intern (TeX-master-file)))
(TeX-MultiTeX TeX-MultiTeX-num-left)))))
(defun TeX-MultiTeX (n)
"Run TeX-command n-times"
(interactive "nRun TeX/LaTeX how many times: ")
(when (or (called-interactively-p 'any)
(null (boundp 'TeX-MultiTeX-num-left)))
(setq TeX-MultiTeX-num-left n))
(if (>= TeX-MultiTeX-num-left 1)
(progn
(TeX-command TeX-MultiTeX-Command 'TeX-master-file)
(setq TeX-MultiTeX-num-left (- TeX-MultiTeX-num-left 1))
(setq proc (get-buffer-process (current-buffer)))
(setq TeX-MultiTeX-sentinel (process-sentinel proc))
(set-process-sentinel proc 'TeX-MultiTeX-sentinel))))
It seems that you need a synchronous way to run TeX-command. I haven't word with TeX-command, but if it uses the compilation API, it can be made to wait for the compilation to finish, although it's not exactly obvious how to do that. Here is an example that uses compilation-finish-functions to achieve the desired effect:
(require 'cl) ; for lexical-let
(defun compile-and-wait (compilefun)
(interactive)
(lexical-let ((done nil) finish-callback)
(setq finish-callback
;; when the compilation is done, remove the callback from
;; compilation-finish-functions and interrupt the wait
(lambda (buf msg)
(setq compilation-finish-functions
(delq finish-callback compilation-finish-functions))
(setq done t)))
(push finish-callback compilation-finish-functions)
(funcall compilefun)
(while (not done)
(sleep-for .1))))
EDIT
AUC TeX is not using compilation mode to spawn TeX, so the above cannot work. Since it's still useful for other compilation buffers, I'm leaving it in the answer. Another way to implement TeX-MultiTeX is by binding TeX-process-asynchronous to nil, which should ensure that AUC TeX waits for the command to finish.

Emacs completion-at-point-functions

I'm writing a derived mode, based on comint-mode. The mode is an interface to a command line program (GRASS gis), and the comint mode completion works for the programs. I'm trying to add on support for completing the arguments to the program, via completion-at-point-functions. A toy example is:
(setq my-commands
'(("ls"
("my-completion-1")
("my-completion-2"))
("mv"
("my-completion-3")
("my-completion-4"))))
(defun my-completion-at-point ()
(interactive)
(let ((pt (point)) ;; collect point
start end)
(save-excursion ;; collect the program name
(comint-bol)
(re-search-forward "\\(\\S +\\)\\s ?"))
(if (and (>= pt (match-beginning 1))
(<= pt (match-end 1)))
() ;; if we're still entering the command, pass completion on to
;; comint-completion-at-point by returning nil
(let ((command (match-string-no-properties 1)))
(when (member* command my-commands :test 'string= :key 'car)
;; If the command is one of my-commands, use the associated completions
(goto-char pt)
(re-search-backward "\\S *")
(setq start (point))
(re-search-forward "\\S *")
(setq end (point))
(list start end (cdr (assoc command my-commands)) :exclusive 'no))))))
(push 'my-completion-at-point completion-at-point-functions)
This almost works. I get normal completion of program names. However, if I have entered ls at the command line, hitting tab inserts my-completion- and doesn't offer the two options. Hitting tab again inserts my-completion- a second time, so that I now have ls my-completion-mycompletion-.
My actual code includes a few lines to check for multi-line commands, but makes no changes to the completion code. With this version of the code, I hitting tab on a line that starts with one of the program names in my-commands I am presented with a list of the possible arguments to complete the command with, but nothing is inserted in the buffer, and the list does not get narrowed by typing the first few letters of an argument.
I've been over the manual, but I can't figure out the correct way to write a completion-at-point function. Any ideas what I'm missing?
I have looked briefly at pcomplete, but the didn't really understand the 'documentation', and didn't make any progress.
The problem seems to be with the way you're finding start and end to return the boundaries of the argument at point. I didn't spend long enough debugging it to be sure of the details, but I think if you call the function interactively you'll see that it returns the same value for start and end, and this means that the completion UI doesn't know to use the argument at point to select from the completion table you've passed it.
Changing the last part of your function to the following seems to be one fix:
(when (member* command my-commands :test 'string= :key 'car)
;; If the command is one of my-commands, use the associated completions
(goto-char pt)
(let ((start
(save-excursion
(skip-syntax-backward "^ ")
(point))))
(list start pt (cdr (assoc command my-commands)) :exclusive 'no)))))))
This gives the expected results when added as an element of completion-at-point-functions.
Here I've used skip-syntax-backward instead of regexp search, which I think is slightly more idiomatic Elisp for this kind of thing. It just says to move point backwards across anything that is not in syntax class "whitespace". The skip-syntax functions return the distance moved rather than the value of point, so we have to add a call to point at the end of the save-excursion.
If you do use regexp searches in a function like this, it's usually a good idea to pass t for the fourth argument, noerror, so that it doesn't pass on errors to the user if it fails to match. This does mean that you have to check for yourself whether the return value is nil, though.
Finally, instead of push to add the completion function you might want to use add-hook as follows:
(add-hook 'completion-at-point-functions 'my-completion-at-point nil t)
This does two useful things: it checks whether your function is already in the hook before adding it, and (by passing t for the fourth argument, local) it only adds the function to the buffer-local value of the completion-at-point hook. This is almost certainly what you want, since you don't want to use these completions in every other Emacs buffer when you press the TAB key.

Copy Character Down in Emacs

I wrote an interactive function which inserts the "character above the point" in to the current line. For instance, given a line containing "12345" followed by a line "abcdef" and the point sitting at the letter "c", copy-down would make the second line become "ab3cdef". copy-down again would make the second line become "ab34cdef".
My function fails (using GNU Emacs 23.3.1 under windows 7) the second time I invoke it by inserting the text from the first invocation and not advancing properly. If I put any emacs "manipulations" in-between invocations, it works fine. (For instance if I do a copy-down, "left arrow", "right arrow", copy-down it works fine for both invocations.)
Here's my function:
(defun copy-down ()
"Grab the character in the line above and insert at the current location."
(interactive)
(let ((beg (progn (previous-line 1) (point)))
(end (progn (forward-char) (point))))
(backward-char)
(next-line 1)
(insert-buffer-substring (current-buffer) beg end)))
If it matters, I usually tie my function to a key: (global-set-key [f5] 'copy-down)
PS. I got used to using this capability in the editor I used before switching to emacs many years ago and I miss it in GNU Emacs. :-(
What you have works just fine for me. That said, previous-line has interaction with other settings (specifically goal-column) and generally shouldn't be used when writing elisp. Instead you should use (forward-line -1). But, of course, your code relies on the goal-column... You can test this by running Emacs without your other configurations, ala emacs -q.
Here's a slightly different version of your code that doesn't rely on goal-column:
(defun copy-down ()
"Grab the character in the line above and insert at the current location."
(interactive)
(let* ((col (current-column))
(to-insert (save-excursion
(forward-line -1)
(move-to-column col)
(buffer-substring-no-properties (point) (1+ (point))))))
(insert to-insert)))
If the problem isn't with using previous-line, then I don't imagine my code would make much of a difference.
Another option you have is to try running it in the debugger to see where your code breaks down. Move the point inside the defun for copy-down and type M-x edebug-defun, and the next time you run it you'll be able to step through the code. Docs for edebug can be found here.
You need to use let* instead of let. The former allows you to use earlier values in later forms in the same statement.
BTW, that's an unconventional way to write elisp, you might want to look at some other code samples.
EDIT:
Hey, someone completely rearranged your function! It might work now.
Try
(defun copy-down (arg)
(interactive "p")
(let ((p (+ (current-column) (point-at-bol 0))))
(insert-buffer-substring (current-buffer) p (+ p arg))))
which has the additional functionality of taking a prefix argument to copy n (default to 1) characters down.