Re: Code folding in Emacs.

[Hongyi Zhao]

On Sun, Oct 10, 2021 at 7:37 PM tolugboji <tolugboji@protonmail.com> wrote:
>
> Emacs should develop code folding (opening and closing) to also work with the 
> mouse.

The code snippet I posted above is based on an idea here [1], as shown below:

--------------

Outlines and Overviews

SelectiveDisplay – a poor-man’s OutlineMode. It hides lines with more
than the provided number of spaces in front. It can help in getting a
quick overview of files as long as paragraph lines are further
indented than headlines. This is great for viewing man pages: ‘C-u 1
M-x set-selective-display’ to show only headings, `M-x <up> RET’ to
disable it again.
More SelectiveDisplay: ‘set-selective-display’ is `C-x$’ by default.
You can make it a lot friendlier with a wrapper: – DaleWiles

            (global-set-key "\C-x$" 'set-selective-display-dlw)
            (defun set-selective-display-dlw (&optional level)
              "Fold text indented more than the cursor.
            If level is set, set the indent level to level.
            0 displays the entire buffer."
              (interactive "P")
              (set-selective-display (or level (current-column))))
--------------

It seems the idea was initiated by DaleWiles, but his/her homepage
given on emacswiki [2] is empty.

Another note, though there are already several code-folding relevant
packages available on melpa [3-5]. In my opinion, this concise and
clear code snippet is suitable for any programming language that uses
indented semantic blocks, and it beats all relevant packages found on
melpa.

[1] https://www.emacswiki.org/emacs/EmacsNiftyTricks#h5o-6
[2] https://www.emacswiki.org/emacs/DaleWiles
[3] https://github.com/gregsexton/origami.el
[4] https://github.com/matsievskiysv/vimish-fold
[5] https://github.com/emacsorphanage/yafolding

HZ

>
> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
>
> On Sunday, October 10th, 2021 at 8:16 AM, Hongyi Zhao <hongyi.zhao@gmail.com> 
> wrote:
>
> > I just found the following code snippet from here [1] for code folding in 
> > Emacs:
> >
> > (global-set-key (kbd "<C-f5>") 'set-selective-display-dlw)
> >
> > (defun set-selective-display-dlw (&optional level)
> >
> > "Fold text indented same of more than the cursor.
> >
> > If level is set, set the indent level to LEVEL.
> >
> > If 'selective-display' is already set to LEVEL, clicking
> >
> > F5 again will unset 'selective-display' by setting it to 0."
> >
> > (interactive "P")
> >
> > (if (eq selective-display (1+ (current-column)))
> >
> > (set-selective-display 0)
> >
> > (set-selective-display (or level (1+ (current-column))))))
> >
> > The above code trick seems very simple, but it works for many
> >
> > languages. So I recommend it here.
> >
> > [1] https://discourse.julialang.org/t/code-folding-for-emacs/41421/3
> >
> > Regards
> > ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> >
> > Assoc. Prof. Hongyi Zhao hongyi.zhao@gmail.com
> >
> > Theory and Simulation of Materials
> >
> > Hebei Vocational University of Technology and Engineering
> >
> > No. 473, Quannan West Street, Xindu District, Xingtai, Hebei province