How to disable underscore (_) subscripting in Emacs, TeX input method - emacs

On Emacs, while editing a text document of notes for myself (a .txt document, not a .tex document), I am using M-x set-input-method Ret TeX, in order to get easy access to various Unicode characters. So for example, typing \tospace causes a "→" to be inserted into the text, and typing x^2 causes "x2" to be inserted, because the font I am using has support for Unicode codepoints 0x2192 and 0x00B2, respectively.
One of the specially handled characters in the method is for the underscore key, _. However, the font I am using for Emacs does not appear to have support for the codepoints for the various subscript characters, such as subscript zero (codepoint 0x2080), and so when I type _0, I get something rendered as a thin blank in my output. I would prefer to just have the two characters _0 in this case.
I can get _0 by the awkward keystroke sequence _spacedel0, since the space keystroke in the middle of the sequence causes Emacs to abort the TeX input method. But this is awkward.
So, my question: How can I locally customize my Emacs to not remap the _ key at all when I am in the TeX input method? Or how can I create a modified clone (or extension, etc) of the TeX input method that leaves out underscore from its magic?
Things I have tried so far:
I have already done M-xdescribe-key on _; but it is just bound to self-insert-command, like many other text characters. I did see a post-self-insert-hook there, but I have not explored trying to use that to subvert the TeX input method.
Things I have not tried so far:
I have not tried learning anything about the input method architecture or its source code. From my quick purview of the code and methods. it did not seem like something I could quickly jump into.

So here is the solution I just found: Make a personalized copy of the TeX input method, with all of the undesirable entries removed. Then when using M-x set-input-method, select the personalized version instead of TeX.
I would have tried this earlier, but the built-in documentation for set-input-mode and its ilk does not provide sufficient guidance to the actual source for the input-methods for me to find it. It was only after doing another search on SO and finding this: Emacs: Can't activate input method that I was able to get enough information to do this on my own.
Details:
In Emacs, open /usr/share/emacs/22.1/leim/leim-list.el and find the entry for the input method you want to customize. The entry will be something like the following form:
(register-input-method
"TeX" "UTF-8" 'quail-use-package
"\\" "LaTeX-like input method for many characters."
"quail/latin-ltx")
Note the file name prefix referenced in the last element in the form above. Find the corresponding Elisp source file; in this case, it is a relative path to the file quail/latin-ltx.el[.gz]. Open that file in Emacs, and check it out; it should have the entries for the method remappings, both desired and undesired.
Make a user-local copy of that Elisp source file amongst your other Emacs customizations. Open that local copy in Emacs.
In your local copy, find the (quail-define-package ...) form in the file, and change the name of the package; I used FSK-TeX as my new name, like so:
(quail-define-package
"FSK-TeX" "UTF-8" "\\" t ;; <-- The first argument here is the important bit to change.
"LaTeX-like input method for many characters but not as many as you might think.
...)
Go through your local copy, and delete all the S-expressions for mappings that you don't want.
In your .emacs configuration file, register your customized input method, using a form analogous to the one you saw when you looked at leim-list.el in step 1:
(register-input-method
"FSK-TeX" "UTF-8" 'quail-use-package
"\\" "FSK-customized LaTeX-like input method for many characters."
"~/ConfigFiles/Elisp/leim/latin-ltx")
Restart Emacs and test your new input-method; in my case, by doing M-x set-input-method FSK-TeX, typing a_0, and confirming that a_0 shows up in the buffer.
So, there's at least one answer that is less awkward once you have it installed than some of the workarounds listed in the question (and as it turns out, are also officially documented in the Emacs 22 manual as a way to cut off input method processing).
However, I am not really happy with this solution, since I would prefer to inherit future changes to TeX mode, and just have my .emacs remove the undesirable entries on startup.
So I will wait to see if anyone else comes up with a better answer than this.

I did not test this myself, but this seems to be the exact thing you are looking for:
"How to disable underscore subscript in TeX mode in emacs" - source
Two solutions are given in this blogpot:
By the author of the blogpost: (setq font-lock-maximum-decoration nil) (from maximum)
Mentioned as comment:
(eval-after-load "tex-mode" '(fset 'tex-font-lock-subscript 'ignore))

The evil plugin for vim-like modal keybinding allows to map two subsequent presses of the _ key to the insertion of a single _ character:
(set-input-method 'TeX)
(define-key evil-insert-state-local-map (kbd "_ _")
(lambda () (interactive) (insert "_")))
(define-key evil-insert-state-local-map (kbd "^ ^")
(lambda () (interactive) (insert "^")))
When _ and then 1 is pressed, we get ₁ as before, but
when _ and then _ is pressed, we get _.
Analogous for ^.

As already explained in pnkfelix answer, it seems we have to make a personalized copy of the TeX input method. But here comes a lighter way to do that, without any file tweaking. Simply put the following in your .emacs :
(eval-after-load "quail/latin-ltx"
'(let ((pkg (copy-tree (quail-package "TeX"))))
(setcar pkg "MyTeX")
(assq-delete-all ?_ (nth 2 pkg))
(quail-add-package pkg)))
(set-input-method 'TeX)
(register-input-method "MyTeX" "UTF-8" 'quail-use-package "\\")
(set-input-method 'MyTeX)
The important part is the assq-delete-all line in the middle that remove all shortcut entries starting with _. It's a bit of a lisp hack but it seems to work. Since I'm also annoyed by the shortcuts starting with - and ^, I also use the following two lines to disable them :
(assq-delete-all ?- (nth 2 pkg))
(assq-delete-all ?^ (nth 2 pkg))
Note that afterwards you can M-x set-input-method at any time and indicate TeX or MyTeX to switch between the pristine TeX input method or the customized one.

Related

Emacs: How to select word under cursor and append to file

I want the following behavior:
Append the word under cursor into a file(~/vocabulary.txt, for example)
Better still to bind a key for it.
Could anyone show me how to do it?
Should I put those code into .emacs ?
Try the following function:
(defun my-write-to-file ()
"Save word at point to file"
(interactive)
(write-region (concat (thing-at-point 'word) "\n") nil "~/vocabulary.txt" 'append))
When called, this function will save the word at point (the word the cursor is on or the word right before the cursor) to ~/vocabulary.txt.
You can bind it to a key (C-c w in this case, but you can change it to whatever you like) like this:
(global-set-key (kbd "C-c w") 'my-write-to-file)
To use, simply put the function and the keybinding assignment in your .emacs.
#Elethan wrote you a command that does just what you ask for, and bound it to a key.
It might also help to mention some general commands that you can use for this kind of thing. M-x append-to-file appends the region contents to a file, and M-x write-region prepends.
The manual is your friend for things like this. See nodes Misc File Ops and Accumulating Text.
Be aware too that for the two commands just mentioned, as the manual says about append-to-file (it should say it about both):
You should use append-to-file only with files that are not being
visited in Emacs. Using it on a file that you are editing in Emacs
would change the file behind Emacs’s back, which can lead to losing some
of your editing.
Accumulating Text also tells you about commands for adding text to a buffer, including the case of adding to a buffer for a file that you are visiting (as opposed to what the above quote warns you about for append-to-file). These include commands append-to-buffer and prepend-to-buffer.

Emacs code completion for .org files

I am using emacs and have code completion working. This works nicely
on source code files .f, .c, ... However it does not complete for
.org files. Is there a command I can put in my .emacs file to solve the problem?
Expanding words that already exist in the file is easy. Use dabbrev-expand, bound to M-/ by default:
Expand previous word "dynamically".
Expands to the most recent, preceding word for which this is a prefix. If no suitable preceding word is found, words following point are considered. If still no suitable word is found, then look in the buffers accepted by the function pointed out by variable `dabbrev-friend-buffer-function'.
If you want to see all options, use dabbrev-completion (C-M-/) instead:
Completion on current word. Like M-/ but finds all expansions in the current buffer and presents suggestions for completion.
Expanding code defined in other buffers will be trickier, and I don't have a good solution for it.
This has solved the problem
(define-globalized-minor-mode real-global-auto-complete-mode
auto-complete-mode (lambda ()
(if (not (minibufferp (current-buffer)))
(auto-complete-mode 1))
))
(real-global-auto-complete-mode t)

How to change Hash color in rhtml-mode in Emacs

I'm using rhtml-mode in Emacs.
When I write a Hash in a way like :key => "value" then :key is properly colorized.
But with key: "value" style the colorizing doesn't work. Only color of : is changed.
I tried to change rhtml-mode a bit. The mode seems to load ruby-mode internally if the text if is braced in <% %> tag.
Oddly when I write a Hash in ruby-mode both type of writing are properly colorized.
I'm using default ruby-mode in Emacs24.
How can I find the place (by line number) where the color of Hash key is defined?
The short answer: C-h vrhtml-in-erb-keywords. This will open a buffer showing you the regexp for rhtml keywords. There will be a link straight to where it is defined in the elisp file. You can see its definition here.
Add the following to your .emacs file:
(add-hook 'rhtml-mode
(lambda ()
(font-lock-add-keywords nil
'(("\\([0-9a-zA-Z_]*:\\)" 1
font-lock-constant-face t)))))
This will make Emacs apply the colouring determined by font-lock-constant-face to anything that matches the regexp "\\([0-9a-zA-Z_]*:\\)". This might match more than you want, so you may want to fine tune it.
I'm not sure there's a particularly easy way to find out exactly where the colour for a given keyword is found. You can always do M-xdescribe-face with the point over the word you want information on. This will tell you how Emacs thinks it should be coloured - something like font-lock-keyword-face. C-h vfont-lock-keyword will tell you how Emacs decided that, but not in a very helpful way.
The simplest way is probably just to open the source code for the mode you're in and search in that for where it defines keywords. You can open the source code with C-h frhtml-mode, which will open a help buffer with a link to the source.

Setting up RefTeX Tab completion in emacs

I am trying to make Tab completion work with RefTeX. When typing C-c [ and selecting the type of reference I have then a prompt in the minibuffer. When I know the beginning of the bib key I want to enter, say for instance Campbell2006, I would like to type Camp Tab and get Campbell2006 [sole completion].
I have managed to set it up for some documents but I do not understand exactly why it works for them and not for others. I have noticed that for the documents that have proper Tab> completion, the following line is added to the file name_of_tex_file.el created in a auto subfolder:
(TeX-add-style-hook "name_of_tex_file"
(lambda ()
(LaTeX-add-bibliographies
"absolute_path_to_bib")))
I think I obtained this results by adding %%% reftex-default-bibliography: absolute_path_to_bib at the end of my files but this is kind of a nuisance, especially when editing the same file on several computers.
Note that RefTeX is working because when I type C-c [ Camp Ret, I get a list (sometime a bit odd) with the Campbell2006 entry.
I have tried to set the %BIBINPUTS% environment variables with no success.
Adding (setq reftex-bibpath-environment-variables '("c:/path_to_bib_file/")) seemed necessary for the C-c [ Camp Ret method to work.
It has somehow the same defects as adding a %%% reftex-default-bibliography: to the end of the file and did not provided the Tab completion.
I have tried various combinations of /, //, \\ and \ as file separators when specifying files but I do not know exact which I should use (I'm using emacs in a windows environment). The issue might be as simple as that but as there are lots of parameters to try I fail do determine where is the problem.
What is the step-by-step method to make RefTeX work smoothly with bibliography, including the Tab completion?
EDIT:
Completion is possible according to the Reftex manual entry about the command reftex-citation:
The regular expression uses an expanded syntax: &&' is interpreted as and. Thus,aaaa&&bbb' matches entries which contain both aaaa' andbbb'. While entering the regexp, completion on knows [sic] citation keys is possible. `=' is a good regular expression to match all entries in all files.
it does not provide precise guidance on how to make it work though.
Kindahero suggests setting a list of the bib entries and use the completing-read command. This sounds sensible, however I would like to generate this list automatically and it seems feasible because it works with some of my documents.
The documentation of reftex-citation is a bit confusing. It promises completion on known citation keys but I believe "known" refers to keys that have been used previously in this session rather than all keys in the appropriate bibliography. You can use the LaTeX-add-all-bibitems-from-bibtex command defined below to load all keys in your bibliography:
(defun get-bibtex-keys (file)
(with-current-buffer (find-file-noselect file)
(mapcar 'car (bibtex-parse-keys))))
(defun LaTeX-add-all-bibitems-from-bibtex ()
(interactive)
(mapc 'LaTeX-add-bibitems
(apply 'append
(mapcar 'get-bibtex-keys (reftex-get-bibfile-list)))))
Suggestions on appropriate hooks to make this happen automatically are welcome.

Modify Alt+f in Emacs for tex-mode

Alt+f in emacs when writing in tex mode seems to not include the . as part of the word. So how do I modify the alt+f behavior to remain the same exact when going forward if there is punctiation to include that as part of the word.
I have a separate file that loads for when writing in tex so I will just throw it in there so it doesn't affect normal emacs behavior.
Thanks for any help.
Thought of an addition to this but same related problem is when using Alt+d and deleting. Getting it to delete not only the word but also the punctation following eg.. (,.! etc..).
The following code should work for you:
(defun unpunctuate-syntax (str)
"Make the characters of the given string word characters."
(let ((st (copy-syntax-table (syntax-table))))
(dotimes (n (length str))
(modify-syntax-entry (elt str n) "w" st))
(set-syntax-table st)))
(defun dots-are-not-punctuation ()
(unpunctuate-syntax "."))
(add-hook 'TeX-mode-hook 'dots-are-not-punctuation)
The way M-f (the forward-word function) works is that it skips all characters in the buffer that have type "w" (ie word) in the current syntax table.
This code makes a modified syntax table and gives it to the buffer and the add-hook bit at the bottom sets it to run when you open a file in TeX-mode. (This method avoids you having to do the separate file thing you described).
You might notice that I make a copy of the syntax table rather than editing the one belonging to the TeX major mode. This is because I always get things wrong when playing with syntax tables and you can mess things up royally... This method means you just have to close the buffer and start again!