There are several questions on SO about how to get code folding in emacs, without having to add any special characters like "markers" in the comments for example. Someone said that there was "no perfect solution."
It seems that it could be done by parsing the source of the program being written and look for matching parenthesis or bracket, or to do it based on indentation. You could also use a combination of scripts that use different methods.
So why is it commonly accepted that there is no "perfect" and straightforward way to get code-folding in emac? Is there something in emacs or its architecture that makes it hard to program? If it were easy, after so many years of smart people using emacs you would think that someone would have wrote it.
You should play with Hideshow (hs-minor-mode) combined with fold-dwim.el. It does exactly what you suggested -- looks for matching braces/parens, and can be set up to fall back on the indentation.
There's a robust folding solution out there for most common languages, and if there isn't, all the folding packages are highly customizable. In fact, the only downside is the proliferation of folding methods (fold-dwim helps quite a bit with that); I used to think that because nobody could point me to a definitive solution, folding was hard or impossible — in fact, the opposite is true. You just have to experiment a little to see what works best for you.
I have used folding.el (e.g. to group stuff in my .emacs), outline-minor-mode, and now Hideshow. There's some chance that none of them would work exactly the way you want right out of the box (e.g. you might need to set up an outline regex, or define folding marks for folding.el), but it turns out to be easy. The default keybindings can be somewhat baroque, but this is remedied by fold-dwim and/or hideshow-org (highly recommended for Hideshow, cf the Emacswiki hideshow page; you can also mimic hideshow-org's behavior for other folding modes with some quick-and-dirty elisp and fold-dwim). Once you figure out your preferred setup, just turn it on automatically via hooks or buffer-local variables, and watch your code fold away :)
You should look into CEDET. It does code-folding just fine, and many other fancy features that you're probably looking for if you're switching from an IDE to Emacs.
http://cedet.sourceforge.net/
Specifically, look for `global-semantic-tag-folding-mode'
You don't need anything extra, just enable outline-minor-mode for file types you want to fold.
But in fact, there ARE various solutions for Emacs; I have listed some of them (those I have happened to come across) at http://en.wikipedia.org/w/index.php?title=Code_folding&oldid=375300945#cite_note-2.
Though, there are things I'm missing: in some cases, I'd like to combine several mechanisms: for example, for markdown, I'd like to use outline-based folding (for sections) and indentation-based folding (for quotations, code blocks etc.) -- in order not bother with implementing a complete parser for markdown.
Here they are:
Token-based folding in Emacs
Token-based folding in Emacs is impemented by the folding minor mode.
Indentation-based folding in Emacs
One can use the set-selective-display function in Emacs to hide lines based on the indentation level, as suggested in the Universal code folding note.
Syntax-dependent folding in Emacs
Syntax-dependent folding in Emacs is supported by:
the outline and allout modes
for special dedicated "outline"-syntaxes;
by the hideshow minor mode for some programming languages;
also,
by the semantic-tag-folding minor mode and the
senator-fold-tag command for
syntaxes supported by semantic,
as well as by doc-mode for JavaDoc or Doxygen comments,
by
TeX-fold-mode
sgml-fold-element command,
nxml-outln library
in the corresponding language-specific modes, and possibly in other modes for particular syntaxes.
Several folding mechanisms are unified by the
fold-dwim interface.
See also http://www.emacswiki.org/emacs/CategoryHideStuff.
Folding of user-selected regions in Emacs
Folding of user-selected regions in Emacs is implemented by the hide-region-hide command.
I have been using folding-mode for quite some time. With auto-insert template and abrevs it works quite well for me for for some nice bricks of code.
Being able to produce the buffer folded (for printing/emailing) has always been a desire of mine. Some of my folding tags are for secure / password hiding.
I know this is a bit old but for me origami.el works perfectly well out of the box.
Yes Finally code folding is there in emacs. Try yafolding present at melpa.org package library.
Related
Emacs newbie here. I have recently switched to (Doom) Emacs and decided to add syntax highlighting to V files. There's already a mode that does that (vlang-mode), but I didn't like it, so I decided to make my own one. The problem is, that, as you probably know, Emacs' regex doesn't support lookaround, which I find essential for stuff like (proper) function higlighting, among others.
So, I have found info about Font Lock mode and (in general words) how to use it. Also, I found a solution to regex problem in using visual-regexp-steroids. The only problem is, I can't figure out how to apply highlighting to regions that it finds.
Links to learning resources would be appreciated.
As described here, emacs-lisp-mode provides for special handling of s-expressions in docstrings that start in the first column. This requires them to be escaped with a backslash to avoid mucking up font-lock later on in the file.
This may be a feature for elisp, but is unfortunate in other lisp modes that reuse emacs-lisp-mode for convenience that don't have special handling of expressions in docstrings, as described/shown here.
My question is, is there any way for such "descendant" modes to configure emacs-lisp-mode to disregard "calling convention expressions" in docstrings?
The short answer is no.
The longer answer is that those other modes are simply broken. They should adapt to Emacs Lisp in this regard. There is no reason not to, is there? It is simply a bad idea to use workarounds (e.g. indent all doc-string lines), such are suggested in the link you provided (and its linked duplicate post).
Emacs doc string are not trivial strings. They have several special properties, including the handling of \\[...], \\{...}, and \\<...>, as well as the property you mention here.
If some mode cannot adjust to Emacs doc strings then it should use macros that define the things it needs without creating Emacs doc strings for them but by handling a different string argument in the special way desired. IOW, create pseudo doc strings that correspond to what the mode wants instead of what Emacs wants.
Of course, that means that you cannot directly take advantage of the Emacs documentation features. You would need to also define mode-specific doc commands that would, for example, wrap the existing doc functions such as describe-function with code that picks up the mode's pseudo-doc string and DTRT, following the mode's conventions instead of the Emacs doc-string conventions.
But I would think that the easiest approach would be to just adapt the mode to the existing Emacs behavior, so that it DTRT.
Many Emacs programming modes, and various Lisp modes are no exception, have been implemented based on parsers with regular expressions. This, unfortunately, gives the editor little idea of the document being edited. Eclipse, for example, has a very different idea of how to edit code, which is more structured, and JetBrain MPS editors are even more rigid and structured in this sense (almost like spreadsheets).
This makes Emacs modes faster and easier to implement, but it also means the code that supports the proper indentation, syntactic validation and highlighting has to re-parse more text every time it is being edited. CEDET, afaik, is trying to address this issue.
Thus, historically, there had been conventions designed to reduce the amount of code to parse on each edit. Parenthesis in the first column is one such convention. However, it also has been known to be an annoyance some times, that's why there's a open-paren-in-column-0-is-defun-start variable one can set to nil to inhibit this behaviour.
But It's hard to say what exactly the performance issues you may face when changing this setting. Lisp grammar is very regular, unless you are using many reader macros, so, perhaps, that won't be a problem.
If beginning-of-defun-function is set accordingly, i.e. checking if inside a comment or string, should be no need for such escaping.
I'm trying to write a new emacs mode for a new template c-like language, which I have to use for some academic research.
I want the code to be colored and indented like in c-mode, with the following exceptions:
The '%' is not used as an operator, but as the first character in some specific keywords (like: "%p", "%action", etc.)
The code lines do not end with a semicolon.
Is it possible to create a derived-mode (from c-mode) and set it to ignore the original purposes of '%' and ';'? Is it possible to make the feature of "automatic-indentation after pressing RET" work without ';'?
Are there similar modes for similar languages (with '{}' brackets, but without semicolons) that I could try to patch?
Should I try to write a major mode from scratch?
I thought about patching the R-mode from http://ess.r-project.org/, but this mode does not support comments of the form "/* comment */".
The most important feature that I'm looking for is the brackets-indentation, i.e. indenting code inside a '{}' block after pressing RET (and without the extra-indentation after lines that do not end with ';'). Partial solutions will help too.
More generally, CC-mode has been extended and generalized over time to accomodate ever more languages, and the latest CC-mode is supposed to be reasonably good at isolating the generic code from the language-specific code. So take a look at some of the major modes that use CC-mode (e.g. awk-mode), and get in touch with CC-mode's maintainer who will be able to help you figure out hwo to do what you want.
If you don't mind something really simple, you can look at Gosu mode. Gosu is a language that has curly braces and no semi-colons, so you should be all set for your minimum. It also uses the same comment syntax as C.
The implementation of the mode for it is really simple and based on generic mode, so modifying it to work the way you want should be easy. It is not based on C-mode.
This is what I used to make a mode for the language I was working on for my compilers class, and it was really easy even with limited elisp experience. On the other hand, the indentation is fairly simple--it works for most code, but is not as complete as C-mode's.
Check out arduino-mode: https://github.com/bookest/arduino-mode/blob/master/arduino-mode.el
It is a C based mode that uses the cc-mode features to quickly create something very useful and unique to arduino programming. Using this as a simple template should help a lot.
When I run Emacs command ispell-buffer on an Emacs buffer which is in the LaTeX mode, ispell checks spelling also inside math expressions.
I'd very much like to disable this. Is there an easy way to do it?
I've read about detex but detex does not seem to be integrated into Emacs.
It shouldn't do this, if you are using latexisms (eg. \[ ... \], equation environments, &c) to invoke math mode. Check the contents of ispell-tex-skip-alists; cf. section 6 of the ispell FAQ for what kind of thing should be there.
You can use $..$, $$..$$ to mark out maths using ispell-tex-skip-alists, but beware getting them out of kilter...
Postscript
Check also the value of the ispell-parser variable: this should be 'tex, otherwise ispell will not look for $...$ and $$...$$ regions.
Yes, you can: install aspell instead of ispell, and use flyspell with it.
This doesn't answer your question directly, but I have found Flyspell, an on-the-fly spell checker, incredibly useful when editing LaTeX documents. It still spellchecks inside equations, but it is much easier to ignore a few extra red underlines than ispell's interactive commands.
You may know this, but you can press A during spell checking to add a word to the buffer-local dictionary (that's capital A, lowercase a adds it to the global dictionary). It's not ideal, but this is how I usually suppress spell-checking of technical terms and variable names, etc., in my LaTeX documents.
This AUCTeX mailing list thread : "spell checker (ispell-buffer) complains about products in math modes" has some workarounds and the answer demonstrates how to use ispell-tex-skip-alists.
Another approach is to use ispell-skip-region-alist. The following example is to exclude org-mode src blocks:
(add-to-list 'ispell-skip-region-alist '("#\\+begin_src". "#\\+end_src"))
I want to fully-justify latex code on EMACS so that my latex code will look better. For example, I remember my advisor sending me latex in fully justified way like this:
In ~\cite{Hummel2004}, authors described an approach for harvesting
software components from the Web. The basic idea is to use the Web as
the underlying repository, and to utilize standard search engines,
such as Google, as the means of discovering appropriate software
assets. Other researchers have crawled through Internet publicly
available CVS repositories to build their own source code search
engines (e.g., SPARS-J)~\cite{Matsushita2005}.
I suppose that his column-width is set to 70 columns.
Could someone give me a hint?
The standard fill.el package includes the command justify-current-line which is part of what you need. From the function help:
Do some kind of justification on this line.
Normally does full justification: adds spaces to the line to make it end at
the column given by `current-fill-column'.
Optional first argument how specifies alternate type of justification:
it can be `left', `right', `full', `center', or `none'.
If how is t, will justify however the `current-justification' function says to
And other posters have already given you the magicall invokation:
M-x set-justification
As a philosophical side note, the point of fixed-wdith text justification is to fake real typography on a inflexible output device. So applying it to LaTeX source seems a little odd to me. Moreover, I have been using the "one sentence to a line" approach to LaTeX documents for some months now, and find that it really does improves both the editability and the source-control behavior of LaTeX, so I would recommend against doing this.
If you select the region, and then press Ctrl-u M-x fill-region you get "full justification".
M-x set-justification-full
Use Refill mode afterwards to not have to run the command again after typing.
To get line wrap in the file itself (as opposed to something like longlines-mode that does not alter the structure of the file), I use auto-fill-mode, which automatically applies M-q (fill-paragraph) to each paragraph. For example, I use auto-fill-mode in mail-mode. You could do something similar with your LaTeX mode with a hook like this:
(add-hook 'TeX-mode-hook 'turn-on-auto-fill)
Assuming your TeX mode's hook is TeX-mode-hook.