[Feature request] Ignore expression (#_) shortcut

[filipesilva]

It would be handy to have a keybind shortcut to ignore an expression via #_ (https://cljs.github.io/api/syntax/ignore). It would be nice for the shortcut to be similar to the current ctrl+/ comment shortcut, perhaps ctrl+shift+/.

Personally I use ; and #_ with different intents: the first is mostly for text comments, the latter for disabling code. Whenever I use ; to disable code I feel I'm only doing it because it's easier (via VSCode shortcuts) than using #_.

But #_ is what I really want for code... because it applies correctly to the whole expression, instead of applying to lines. When I use ; to comment code I must think about start line, end line, and expression delimiters.

A couple of captured scenarios:

Calva has a concept of current form. This is the selected form when using the "expand selection" shortcut (ctrl+w).

If the user has the cursor on 2 in (+ 1 2 3), it is valid to ignore it and get (+ 1 #_2 3).

Regarding selections, consider the following:

(do
  (do 
    (inc 1)
    (inc 2)))

If we select rows 2, 3, and 4, we should get:

(do
  #_(do
    (inc 1)
    (inc 2)))

and not

(do
  #_(do
    #_(inc 1)
    #_(inc 2)))

But if we had select rows 3 and 4, then:

(do
  (do
    #_(inc 1)
    #_(inc 2)))

The comment shortcut also uncomments lines regardless if they are already commented. But since the ignore token "stacks", we shouldn't double ignore expressions. An example:

(do
  (do 
    (inc 1)
    #_(inc 2)))

Selecting lines 3 and 4, and pressing the ignore shortcut:

(do
  (do
    #_(inc 1)
    #_(inc 2)))

Pressing it again:

(do
  (do
    (inc 1)
    (inc 2)))

This was proposed by @AlexVPopov and discussed on the Clojurians slack with @PEZ.

[PEZ]

Cool. Thanks!

[dbodow]

While access to both ; and #_ would be most useful, a lower hanging fruit version of this might be to add an option for users to select the default character for Toggle Line Comment in .clj projects.

In my experience, when using the Toggle Line Comment shortcut, I almost alway intend to block a snippet of code from executing, rather than writing a static comment (which, by its nature, never really needs toggling). If I had the option to always use ignore next form style comments when using the toggling feature, that would be a much better code tinkering experience for me.

I know it's pretty easy to change this within an extension --it's just a matter of exposing that as a choice to the extension user.