Emacs - Multiple columns one buffer - emacs

I'm trying to edit some assembly code which tends to be formatted in long but thin listings. I'd like to be able to use some of the acres of horizontal space I have and see more code on-screen at one time. Is there a method for getting Emacs (or indeed another editor) to show me multiple columns all pointing to the same buffer?
C-x 3 (emacs) and :vsplit (vim) are great for multiple separate views into the code, but I'd like it to flow from one column to the other (like text in a newspaper).

See follow-mode.
Excerpt:
Follow mode is a minor mode that makes two windows, both showing the same buffer, scroll as a single tall “virtual window.” To use Follow mode, go to a frame with just one window, split it into two side-by-side windows using C-x 3, and then type M-x follow-mode. From then on, you can edit the buffer in either of the two windows, or scroll either one; the other window follows it.
In Follow mode, if you move point outside the portion visible in one window and into the portion visible in the other window, that selects the other window—again, treating the two as if they were parts of one large window.

I use this function to invoke follow-mode, although it would need customization for a different screen size:
;;; I want a key to open the current buffer all over the screen.
(defun all-over-the-screen ()
(interactive)
(delete-other-windows)
(split-window-horizontally)
(split-window-horizontally)
(balance-windows)
(follow-mode t))

The "Multipager" plugin for Vim can do this with VIM splits for people who want to get this behavior in Vim.
Get it from Dr. Chip's page: http://mysite.verizon.net/astronaut/vim/index.html#MPAGE
Docs: http://mysite.verizon.net/astronaut/vim/doc/mpage.txt.html

Vim can do this using :vsplit - and you can have the same buffer open in multiple "windows" (which are actually sections within a single "window").
Documentation here

A quick look at the emacs wiki doesn't show a mode like you describe. However, it shouldn't be too hard to write one... You just need to split the window with C-x 3 and move the text in the other window down, and whenever you move the text, do the same to the other window...
Problems may occur when you get to the bottom of the buffer, do you want the cursor to immediately go to the other window at the top?
Hmm, maybe its not that easy. But it should still be doable...

this is the default behaviour of emacs when splitting the window (C-x 3 for vertical split)
you get two columns which both have the current buffer open

Use vertical-split with C-x 3. This will split the current buffer into two columns that you can switch between with C-x o.

Related

Emacs multiple-cursor - Cut and yank in multiple lines

Using the 'multiple-cursor' emacs package,
when I mark a word and cut ('C-w') in different multiple cursors, the only word in the 'active' cursor I control is cut.
I want to select different words in multiple positions and yank it to other relative position.
When I first tried this I remember some yes or no option at the screen bottom, but I couldn't really notice this at first and some keystroke made it to "no". I guess this might have been an option for multiple-cut. But I don't know how to revert this choice.
How do you do multiple cut and yank in emacs?
This works by default, so at some point you have indeed asked the library not do do this.
These settings are stored (by default) in ~/.emacs.d/.mc-lists.el
Just edit that file appropriately, and then M-x eval-buffer RET to make those same changes in the running instance.

Emacs switch-to-buffer (C-x b) will change window if the buffer is opened in some other window

I would like to change the behavior of switch-to-buffer to always open the desired buffer in the current window instead of switching to another window if already opened.
My rationale for doing this :
I have 2 screens, one Emacs on each. One is for reading, the other one for writing. Some buffers will be in the reading side for a while, but now I want to edit them. I'd like to have them in front of me instead of automatically switch to this other window on the side.
Thank you.
That is what switch-to-buffer does - exactly what you say you want. Do you see something different when you start Emacs without an init file (emacs -Q)?
The only exception is when the window cannot be used for that buffer. As the doc string says:
If the selected window cannot display the specified
buffer (e.g. if it is a minibuffer window or strongly dedicated
to another buffer), call `pop-to-buffer' to select the buffer in
another window.

Emacs buffer copy with single stroke

assume I have focus on BrokerSyncMasteredRecord.cc. I want to fast copy BrokerSyncMasteredRecord.cc to the left by one stroke(like some hotkeys). the final state in pic 2. Currently, I can only use C-x b and type in a few chars of the buffer name. this is very slow.
NOTE: this should not be another opened replica buffer(e.g., BrokerSyncMasteredRecord.cc[replicated], you know what i mean if you are a emacs user) but exact the same buffer, just show in two different windows
I'll just quote the Emacs tutorial (f1 t) for you:
* MULTIPLE WINDOWS
------------------
One of the nice features of Emacs is that you can display more than
one window on the screen at the same time. (Note that Emacs uses the
term "frames"--described in the next section--for what some other
applications call "windows". The Emacs manual contains a Glossary of
Emacs terms.)
>> Move the cursor to this line and type C-l C-l.
>> Now type C-x 2 which splits the screen into two windows.
Both windows display this tutorial. The editing cursor stays in
the top window.
This basic tutorial is just 1000 lines, almost small enough to use as a capcha
for asking questions about Emacs:)

Emacs remember text selection

I decided that I was ready to try something new, after a few years of using gEdit for most of my coding needs, and try to learn using Emacs. I knew this would be difficult, as I have heard how complex Emacs can be, but I was lured by its power. The hardest thing has been getting used to writing ELisp in the .emacs file to change things about the editor. I can't currently do it myself, but I have found a few helpful snippets here and there to change some options.
One thing I have been having a lot of problems with is getting Emacs to remember the text I have selected after a command. For instance, I commonly highlight a section of code to mass indent it. However, if I do this in Emacs, it will move the selected text only once before unselecting all of the text. Does anyone know a way around this?
Anyway, I apologize for what seems to me to be an easy question, but after an hour of Google searching and looking around here on SO, I thought it was worth asking. I have a few more questions about Emacs, but I will save them and ask separately after I get this straightened out. Thanks!
UPDATE
A few people have asked about what mod I am using and what type of text I am entering. While I don't know much about Emacs modes, I am editing a pure text file at the moment. Something like this:
Hello, I am a simple text file
that is made up of three separate
lines.
If I highlight all three lines and hit TAB, I get this:
Hello, I am a simple text file
that is made up of three separate
lines.
This is great, however, if I use C-x C-x like some suggest below to reselect the text and hit TAB again, I get this:
Hello, I am a simple text file
that is made up of three separate
lines.
I hope this helps!
FWIW, here is the reason for the behaviour of your newly-added example. (I'm not 'solving' the issue here, but I'm posting it to demystify what you're seeing.)
This was determined with emacs -q which disables my customisations, so the following is default behaviour for emacs 23.2.
You are in text-mode. You should see (Text) or similar in the mode line at the bottom of the screen, and C-h m will tell you (under the list of minor modes) "Text mode: Major mode for editing text written for humans to read." Emacs decides (by way of the auto-mode-alist variable) that it should switch to text-mode if you visit a filename matching certain extensions (such as .txt).
In text-mode pressing TAB with a region highlighted causes indent-according-to-mode to be called on each line of the region in sequence. The slightly convoluted path to finding this out starts at C-h k TAB, which tells us that TAB is bound to indent-for-tab-command, which in this instance calls indent-region -- that function name is not stated explicitly in the help, but can be seen in the code -- which checks the buffer-local indent-region-function variable, which is nil, and: "A value of nil means really run indent-according-to-mode on each line."
indent-according-to-mode checks the indent-line-function variable, which has the buffer-local value indent-relative.
Use C-h f indent-relative RET to see the help for this function. (Read this).
Although you probably won't yet have had the experience to know how to check all that (or necessarily even want to!), and fully understand everything it tells you, this is an example of how the self-documenting aspect of Emacs enables a user to figure out what is going on (which then makes it feasible to change things). I essentially just used C-h k (describe-key), C-h f (describe-function), and C-h v (describe-variable) to follow the documentation. Looking at the source code for indent-for-tab-command was as simple as clicking the file name shown as part of its help page.
I suggest doing the following to help see what is happening when indent-relative runs on each line:
M-x set-variable x-stretch-cursor t
M-x set-variable ruler-mode-show-tab-stops t
M-x ruler-mode
Now for each line in turn, put the cursor at the very start of the line and press TAB. You'll end up with all three lines indented to the first tab-stop ('T' in the ruler).
Now repeat this -- again, ensure you are at the very start of each line, in front of the existing indentation.
The first character of the first line (which is currently a tab) is once again indented to the first tab-stop, as there is no preceding line for it to examine.
Next, the first character of the second line is indented to match the position of the first non-white-space character of the preceding line. Because the first character of the second line is also a tab, the actual text of the second line is pushed one tab further along.
The third line follows suit. Its first tab character is lined up with the first non-white-space character of the second line, with the same relative effect as before, giving you the final state in your example.
To emphasise, note what happens if you now put enter the line "a b c" above the existing lines, then move back to the start of the next line (what was previously the first line) and press TAB. The first tab character will now be indented in line with the 'b'. Provided that the indent-tabs-mode variable is true (meaning you have actual tab characters), then this will have no practical effect on the position of the words in the line, as 'indenting' a tab with spaces will not have an effect until the number of spaces exceeds the width of the tab (but that's another kettle of fish entirely!)
All this really means is that text-mode in Emacs doesn't behave the way you'd like it to in this situation. Other major modes can do completely different things when you press TAB, of course.
As is invariably the case with Emacs, things you don't like can be changed or circumvented with elisp. Some searching (especially at the Emacs Wiki) will frequently turn up useful solutions to problems you encounter.
Try typing C-x C-x after Emacs unselects it.
Then, instead of hitting tab (I never knew that tab does what you said! That's totally whacked.), do M-8 C-x C-i. Pity it's so many keys, but it ought to do what you want -- namely, shove everything over 8 columns. Obviously replace the M-8 with something else if you want some other number of columns.
What I usually do is simply type C-x C-x (exchange-point-and-mark) after a command that deactives the region.
How are you indenting, and in which mode?
The indentation rules in any programming mode should generally just get it right. (If they don't, that's probably more indicative that you want to configure the rules for that mode differently, but I suspect that's a different question which has been asked already).
If you're in text-mode or similar and just using TAB, then I can see the problem.
Note that if you're using indent-rigidly (C-x C-i, or C-x TAB which is the same thing) then you can repeatedly indent the same region simply by repeating the command, even if the highlighting has disappeared from view.
You can also use a prefix arg to indent-rigidly to make it indent many times. e.g. C-u C-u C-x C-i (easier to type than it looks) will indent 16 spaces (4 x 4, as the prefix arg defaults to 4, and it multiplies on each repeat). Similarly, M-8 C-x C-i indents 8 spaces. This is fine in some circumstances, and way too cumbersome in others.
Personally I suggest putting (cua-selection-mode 1) into your .emacs and using that for rigid indentation. Trey Jackson made a handy blog about it. With this, you can C-RET to start rectangle selection, down as many lines as you need, TAB repeatedly to indent the lines, and C-RET to exit the mode.
While the rectangle is active, RET cycles through the corners. For left-hand corners, typing inserts in front. For right-hand corners, typing inserts after. For the single-column rectangle, bottom counts as 'left' and top counts as 'right' for this purpose.
Trey's blog lists all the available features (or look in the source file: cua-base.el)
Be warned that indentation in Emacs is generally an unexpectedly complicated topic.
You can do this with something like the following:
(add-hook 'text-mode-hook (lambda ()
(set (make-local-variable 'indent-region-function)
(lambda (s e)
(indent-rigidly s e tab-width)))))
Then selecting a region and hitting TAB. will indent the region by a tab-width. You can then exchange point and mark with C-x C-x and hit TAB again to repeat.
I do, however, agree with the previous answers that suggest using indent-rigidly directly.

Display same file successive pages on Emacs split screen

I've done this before, years ago, so I know the answer is out there. However the google-space is heavily polluted with namespace collisions, especially new user guides.
This is what I'd like to do in Emacs 21:
Split the screen on a given file buffer (C-x 3).
As I page through the first screen (C-v), the next page of the file is automatically displayed on the second.
To be clear, the next line in the file after the last line on the left screen should be the first line on the right screen, always.
Any help?
You might be looking for follow-mode
It is minor mode that combines windows into one tall virtual window.
You want scroll-all-mode
scroll-all-mode is an interactive compiled Lisp function in `scroll-all.el'.
(scroll-all-mode &optional arg)
Toggle Scroll-All minor mode.
With arg, turn Scroll-All minor mode on if arg is positive, off otherwise.
When Scroll-All mode is on, scrolling commands entered in one window
apply to all visible windows in the same frame.
Set up the windows appropriately, and then turn on scroll-all-mode, and from then on all windows scroll together
If follow-mode doesn't work, you could define your own macro, something like
(defun align-windows ()
(set-window-start (other-window) (window-start))
(scroll-other-window))
Then either use this (along with scroll-down) instead of C-v, or rebind C-v to that, or add
advice to scroll-down.
You can start Follow mode and setting up a basic two-window layout using
M-x follow-delete-other-windows-and-split RET.
it is from http://www.emacswiki.org/emacs/FollowMode