How to prevent `magit-visit-thing` to open an `evil-mode` buffer - emacs

evil-mode has evil-emacs-state-modes var, which defines modes to open in emacs mode.
I have magit-diff-mode listed in that var (in fact, it is a default).
Running magit-diff opens correctly in emacs mode.
However, if I a run magit-status (opens in emacs mode), place the point on Head (first line in the buffer) and hit Ret, magit-visit-thing is called and and the commit info is shown in a new buffer. This buffer is in magit-diff-mode, however, evil-mode is active for this buffer.
How do I prevent this behaviour?

As we figured out in the comments - the buffer opens in magit-revision-mode, not in magit-diff-mode.
To find out the major mode of the buffer, describe variable major-mode - C-h v major-mode <RET>.
For you information, when you do describe-mode instead (C-h m) what you see as mode name is the string that appears in the status line. It may be difficult to guess from it what the actual mode name is - like Magit Rev is actually a string for magit-revision-mode - no way of knowing unless you look in magit-diff.el:
define-derived-mode magit-revision-mode magit-diff-mode "Magit Rev"

Related

How can I get back the "natural" order in the Buffer List?

With C-x C-b the buffer list is displayed. First in it's natural order with most recently used buffers on top, and buried buffers at the bottom.
There, I can now sort the Buffer by name, size, mode and file. But once I click on such an option I cannot go back to the original ordering.
Also killing the buffer and recreating it does not change that order. (Using 25.2)
So how can I get that ordering back without restarting emacs?
There is another mode that's nowadays built-in to Emacs that can be used to display the buffer list: ibuffer-mode.
If you are not using it already, you can experiment with M-x ibuffer and find out its capabilities with C-h m. Note that in particular, it can sort the buffer list in various ways, one of which is by recency with s v, which is what the OP asked for; but note also that it has many other ways to sort that make it very flexible.
Once you are convinced that that's the way to go, you can redefine the C-x C-b keybinding in your init file with:
(global-set-key (kbd "C-x C-b") 'ibuffer)
I did that a long time ago and have never looked back. IMO, it should be the default: that may come to pass, but AFAIK that is still not the case.
Sorting order goes away as expected when I kill buffer named *Buffer List* and reopen using C-x C-b (Using emacs 27.1 & 28.1). From the EmacsWiki
Once sorted, there is no nice way to restore the default MRU sort. You
have to ‘kill-buffer’ the buffer menu buffer, and then re-open it.
(Sorting sets the variable ‘tabulated-list-sort-key’ in
tabulated-list.el. Its default is ‘nil’. No way to restore the nil
value is provided.)
May be worth adding a custom function which can disable the sort without closing the buffer.
(defun disable-buffer-sort()
(interactive)
(save-excursion
(set-buffer (get-buffer "*Buffer List*"))
(setq tabulated-list-sort-key 'nil)
(revert-buffer)
))
(disable-buffer-sort)
As #NickD mentioned in other answer ibuffer-mode is also a good alternative with more features.

How to clear the Emacs buffer history?

When I press C-x b (ido-switch-buffer) I get a lot of buffers that I don't want to see. I'd like to clear the buffer history.
I tried evaluating this expression (using M-x eval-buffer):
(setq ido-buffer-history '())
And it took effect; I can tell because I looked at the variable with C-h v ido-buffer-history. However, the change did not get reflected in the minibuffer when I press C-x b.
What else should I do? Are there other variables I should be clearing?
UPDATE : The 'extra' buffers that I'm seeing are not active. Interestingly, C-x C-b (ido-fallback-command) shows exactly what I would expect. It is the buffer history that I'm interested in. (See the buffer-name-history and ido-buffer-history variables for more context.)
Note: Perhaps it will help to mention that I'm using the emacs-starter-kit which has ido-ubiquitous installed.
Add the following to your init.el: (setq ido-use-virtual-buffers nil)
For posterity:
Those are all the active buffers in your session. You can clean them with the following commands:
M-x clean-buffer-list will close any clean buffers you haven't used in a while
M-x kill-some-buffers will visit each buffer and ask if you want to close it
M-x kill-matching-buffers will prompt for a regex over buffer names, which you can just leave blank
Edit:
There's also the boring old buffer menu you get with C-x C-b. In this menu, you can hold d until it marks each buffer for deletion, then press x to commit.
Thanks to Chris, I learned about ido's virtual buffers. I don't want to disable ido-use-virtual-buffers altogether. I want to clear the history as needed; these commands accomplish that goal:
(setq ido-virtual-buffers '())
(setq recentf-list '())
(Note that clearing ido-virtual-buffers was not sufficient -- recentf-list also must be cleared.)
I found this entry on emacswiki.
The variable that stores the buffer history you are referring to is buffer-name-history
If you run M-x describe-variable RET buffer-name-history RET you will see all of the dead buffers that no longer really exist. The wiki recommends creating a hook that removes the buffer name from the list whenever you kill a buffer.
I just did: M-x eval-expression RET (setq buffer-name-history '()) RET
This seems to have worked. The next time I ran C-x b I only cycled-through my real buffers.
That said, setting the variable to nil seems to completely disable the functionality (the variable doesn't seem to be re-populated once I open more buffers).

How can I more easily switch between buffers in Emacs?

I've recently started using emacs and I'm enjoying using it for the most part. The only thing I'm not enjoying, is switching between buffers. I often have a few buffers open and I've grown tired of using C-x b and C-x C-b, are there any packages that make switching between buffers easier? I've looked into emacs wiki on switching buffers and I'd appreciate insight/feedback on what are are using/enjoying. Thanks.
UPDATE: iswitchb-mode is obsolete in Emacs >= 24.4, replaced by ido.
All of the features of iswitchdb are now provided by ido. Ross provided a link to the documentation in his answer. You can activate with the following in your .emacs (or use the customization interface as Ross suggests):
(require 'ido)
(ido-mode 'buffers) ;; only use this line to turn off ido for file names!
(setq ido-ignore-buffers '("^ " "*Completions*" "*Shell Command Output*"
"*Messages*" "Async Shell Command"))
By default, ido provides completions for buffer names and file names. If you only want to replace the features of iswitchb, the second line turns off this feature for file names. ido will ignore any buffers that match the regexps listed in ido-ignore-buffers.
The behaviour described below for iswitchb-mode applies equally to ido for switching buffers.
iswitchb-mode (Emacs < 24.4)
iswitchb-mode replaces the default C-x b behaviour with a very intuitive buffer-switching-with-completion system. There are more sophisticated options, but I've never needed more than this.
After you hit C-x b, you are presented with a list of all buffers. Start typing the name of the buffer you want (or part of its name), and the list is narrowed until only one buffer matches. You don't need to complete the name, though, as soon as the buffer you want is highlighted hitting enter will move you to it. You can also use C-s and C-r to move through the list in order.
You can turn it on by default with this in your .emacs:
(iswitchb-mode 1)
You can also tell it to ignore certain buffers that you never (or very rarely) need to switch to:
(setq iswitchb-buffer-ignore '("^ " "*Completions*" "*Shell Command Output*"
"*Messages*" "Async Shell Command"))
You can use C-x <right> (next-buffer) and C-x <left> (previous-buffer) to cycle around in the buffer ring. You could bind S-<right> and S-<left> to these functions. (S is the "super-key" or windows-key). This way you can save some keystrokes.
Moreover, note that C-x b has a default entry, i.e. it displays a standard value (most of the time this is the previously viewed buffer), so that you don't always need to enter the buffer name explicitly.
Another nice trick is to open separate windows using C-x 2 and C-x 3. This displays several buffers simultaneously. Then you can bind C-<tab> to other-window and get something similar to tabbed browsing.
M-x customize-group ido then set Ido Mode to Turn on both buffer and file and set Ido Everywhere to on. Then click the Save for future sessions button at the top and enjoy ido magic for both files and buffers. Read the docs to get a sense of how to use ido.
Also, take a look at smex.
ido-mode provides an efficient way to switch buffers.
ibuffer is best for managing all opened buffers.
anything is good for selecting an interested thing from different
sources. (for eg: a single key can be used to switch to another
buffer or to open recently closed file or to open a file residing
in the same directory or ... anything you want ... )
If you've looked at the Emacs Wiki, you probably have all this information already, but here are a few other relevant Q&As:
Emacs: help me understand file/buffer management
Buffer switching in Emacs
How to invoke the buffer list in Emacs
My toolkit consists of ibuffer, windmove+framemove, winner-mode, and a custom binding to make C-xleft/right and C-cleft/right less of a hassle to use.
I have mapped the "§"-key to 'buffer-list and I find it to be very efficient.
I've started using anything for a couple of days and I'm really liking it: http://www.emacswiki.org/emacs/Anything .
Emacs-fu has an good intro to anything: http://emacs-fu.blogspot.com/2011/09/finding-just-about-anything.html
My favourite function for this is helm-mini which is part of helm.
As other helm functions, it allows incremental narrowing of the selection. It also searches your recently visited buffers, which is a really nice way to re-open a buffer. Helm can be a little surprising at first and as a new Emacs user, I found it visually overwhelming and I preferred ido or ibuffer which have been suggested in other replies. But now I absolutely love it and use it all the time for countless things.
Something that I realized by accident and that can be useful:
mouse-buffer-menu is by default bound to <C-mouse-1> (Control key + mouse left click) and opens a popup with a list of the current buffers.

how to stop Emacs from opening new buffers when following a link in customization

The problem occurs when customizing options in Emacs. Every time I click on a link a new buffer is created. How to force Emacs to use single buffer?
Try this:
(defadvice custom-buffer-create (before my-advice-custom-buffer-create)
"Exit the current Customize buffer before creating a new one, unless there are modified widgets."
(if (eq major-mode 'Custom-mode)
(let ((custom-buffer-done-kill t)
(custom-buffer-modified nil))
(mapc (lambda (widget)
(and (not custom-buffer-modified)
(eq (widget-get widget :custom-state) 'modified)
(setq custom-buffer-modified t)))
custom-options)
(if (not custom-buffer-modified)
(Custom-buffer-done)))))
(ad-activate 'custom-buffer-create)
As an alternative to my original answer (which I am not inclined to use myself), I thought I might suggest other ways in which you might deal with getting rid of lots of Customize buffers once you have finished customising things.
First, do note that simply pressing q will "Exit current Custom buffer according to `custom-buffer-done-kill'" (i.e. either bury it or kill it).
Second is to use M-x kill-matching-buffers RET \*Customize RET (and then confirm each one), but that's a bit tedious.
What I'd actually do is use ibuffer.
If you don't use it already, I recommend binding C-x C-b to ibuffer, which is a greatly enhanced alternative to the default list-buffers. I love it primarily for its filtering and grouping abilities, but it can do a great deal besides that.
(global-set-key (kbd "C-x C-b") 'ibuffer)
I also use the advice which can currently be found here at the Emacs Wiki so that ibuffer always opens with the buffer I came from selected.
That done, and from a Customize buffer, C-x C-b * M RET D y will kill all the Customize buffers. That is:
C-x C-b Open ibuffer (with point on the current Customize buffer entry)
* M Mark buffers by major mode...
RET ...select the mode (which defaulted to the major mode of the selected buffer, or otherwise type Custom-mode RET)
D y kill all marked buffers
Try it out; you'll probably like it. Searching for ibuffer will turn up other handy uses.
For instance, you could use / n ^\* RET / g tmp RET to separate out all buffers starting with * into a "tmp" group, so that they don't clutter up the group of buffers you are more likely to be interested in.
As with any major mode, use C-h m to read the built-in documentation.

How do I turn off vhdl-mode in emacs?

I am learning emacs at the moment and tried to write an easy vhdl program for testing. I can see that the vhdl-mode might be an interesting feature, but I would like to know how I can turn it off for the moment and how I can reactivate it later on.
Use the command M-x fundamental-mode, that is:
Press (and hold) the meta key (which is usually the Alt key)
Press x
This will take the cursor into the echo area at the bottom of the screen/frame. Type fundamental-mode and press return.
To disable VHDL mode permanently, you will have to change the file-extension mapping used by emacs to associate a file's extension with a particular major mode. You can do this by writing a custom .emacs configuration file. Look for auto-mode-alist in the emacs manual:
(setq auto-mode-alist (remove (rassoc 'vhdl-mode auto-mode-alist) auto-mode-alist))
Change to some other mode, e.g.
M-x fundamental-mode RET
or
M-x indented-text-mode RET
re-enable it by entering
M-x vhdl-mode RET