I have the following snippet of code:
(defun my-move-line-below ()
(interactive)
(let ((point-from-start (- (point) (line-beginning-position))))
(kill-whole-line)
(next-line)
(move-beginning-of-line nil)
(yank)
(previous-line)
(goto-char (+ (line-beginning-position) point-from-start))))
What it does is it moves the current line below the the next one. It works well, but problem is that when EOF is reached, the function stops after next-line, thus killing the line without yanking it back.
I know I could solve this by checking the line number and such, but I wonder if it is possible to just ignore the error and continue the execution of the function.
I think replacing (next-line) with
(ignore-errors (next-line))
should do the trick.
Just to point out, there is a ready-made function for that, C-x C-t, although it does not remember the point position after transposition.
Related
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 :))
I would like to have a function that moves point to the end of the line (or marks the paragraph) and then evaluates. I got this working, but it does not have the nice error handling like the clean C-x C-e would do. Any ideas how to program this simply?
What is wrong with straightforward definition?
(defun my-eval-last-sexp (arg)
(interactive "P")
(move-end-of-line 1)
(eval-last-sexp arg))
As part of learning ELisp, I am trying to make a function that makes a copy of the current line below the current line (duplicates the line). What I have so far works pretty well, except on the last line of the buffer. If on the last line, then the line just gets pasted at the end of the line rather than below it.
Here is my code:
(defun duplicate-line ()
"duplicate the current line"
(interactive)
(save-excursion
(kill-ring-save (line-beginning-position) (line-beginning-position 2))
(goto-char (line-beginning-position 2)) ; goto the start of the next line
(yank)
)
(next-line)
)
Is there a better way of doing this? I would also appreciate any other advice concerning writing elisp.
I guess this happens only when the last line doesn't end with a newline character.
The following function inserts a newline if necessary, and avoids using the kill-ring.
(defun duplicate-line ()
(interactive)
(let* ((pos-end (line-beginning-position 2))
(line (buffer-substring (line-beginning-position) pos-end)))
(goto-char pos-end)
(unless (bolp) (newline))
(save-excursion ;; leave point before the duplicate line
(insert line))))
You could do instead:
(kill-whole-line)
(yank)
(yank)
to the same effect. But, perhaps, if I was to write such a function, I'd rather make it so the line isn't copied to the kill-ring. Usually, if I need to duplicate line, I don't want it to be there.
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.
After upgrading to emacs 23.2.1 with Fedora 15 one of my emacs functions is broken and I just can't seem to find the problem. Something has to have changed, but I sure can't find it in the elisp documentation.
I'd really appreciate any suggestions!
What it should do: Pressing Ctl-hyphen should copy the character above the cursor and move the point ahead by 1.
What it does: Keeps copying the character above without advancing the point. HOWEVER, calling it with "M-x insert-char-from-previous-line" or pressing RightArrow between Ctl-hypens works as it should. Adding (forward-char 1) to the end of the script doesn't help.
(defun insert-char-from-previous-line ()
"Copy previous line character by character"
(interactive)
(previous-line 1)
(let ((char-above (following-char) ))
(next-line 1)
(if (not (char-equal char-above ?\n ))
(insert char-above))))
(global-set-key [?\C--] 'insert-char-from-previous-line) ;copy char above
I think your getting caught in a goal column issue. You probably should not use next-line/previous-line for this, rather try this:
(defun insert-char-from-previous-line ()
"Copy previous line character by character"
(interactive)
(let ((curpoint (point))
(curcolumn (current-column)))
(forward-line -1)
(forward-char curcolumn)
(let ((char-above (following-char) ))
(goto-char curpoint)
(if (not (char-equal char-above ?\n ))
(insert char-above)))))
From the docs on pervious-line:
If you are thinking of using this in a Lisp program, consider using
`forward-line' with a negative argument instead. It is usually easier
to use and more reliable (no dependence on goal column, etc.).
(describe-function 'previous-line)
don't move the point for something like this:
(defun i-char (arg)
(interactive "*p")
(let ((start (+ (point-at-bol 0)
(current-column)))))
(insert (buffer-substring-no-properties start (+ start arg))))