Re: Explain a bit more on how to configure language server in Eglot's manual

[Yuan Fu]

> On Mar 8, 2023, at 11:43 AM, João Távora <joaotavora@gmail.com> wrote:
> 
> On Wed, Mar 8, 2023 at 3:01 PM Augusto Stoffel <arstoffel@gmail.com> wrote:
> 
>>> I don't understand: didn't you state you _like_ dotted notation?
>> 
>> Yes, as a quick fix.  But you and the circumstances showed that it isn't
>> nearly good enough.
> 
> OK.  Then we'll hold that idea back.  AFAICT, Yuan also is also a fan
> of that notation, so maybe he can chime in.
> 
>>> A special plist editing mode for a single Eglot variable falls into
>>> that category, IMNSHO.
>> 
>> By the way, my suggestion is to edit a JSON value, which is what the
>> server receives, you can copy and paste from other places, and doesn't
>> require you to know jsonrpc.el internals such as :json-false and the
>> translation of nil.
> 
> They are not internals.  They are the external, published and documented
> way to create JSON for jsonrpc.el contexts.  The documentation isn't
> great, I know.  This is precisely what this thread is originally about
> and I'm working on it.
> 
>>> and I don't see any other good place to put a single utility function
>>> that facilitates it but in Eglot.
>> 
>> The utility function belongs to map.el.  It is called `assoc-in` in
>> Clojure.
> 
> Yuri presented some pretty good arguments about how that would
> be a bad idea.  Also, not a Clojure expert, but AFAIK that
> function doesn't take dotted notation strings as input.
> 
>> Speaking of bloat, and I know I shouldn't insist, but a basic version of
>> the savable eglot-show-workspace-configuration barely adds 30 LOC.
> 
> Your code has at least two big problems:
> 
> * it takes the current value from one place and
>  potentially saves it in another place.  This is asking
>  for trouble.  I know you favour the 'nil' method exclusively
>  for setting e-w-configuration, but it's not the only supported
>  methods and there are configurations out in the wild that
>  we can't break. Also note the that per-file or per-sub-hierarchy
>  workspace configurations _are_supported by LSP (the scopeUri
>  argument to the workspace/configuration server request).
> 
> * it doesn't take into account dir-local-set-class-variables
> 
> These are exactly the type of edge cases that I don't want
> to handle in Eglot.  In other words, Emacs has many variable
> setting methods and making an Eglot function to oversimplify
> them, even if it happens to work for an estimated majority of
> cases, is a bad idea, simply because it will break a minority.
> 
> That said, your code has great ergonomics and you seem to be
> a very able Elisper.  So I'll restate: if a generic, safe
> version of this hits Emacs libraries, Eglot will be happy to
> use it and I at least will be very grateful for that contribution.
> 
> A better dir-local editing facility would account for (at least)
> those two cases.  Even if that accounting is, at first, just bailing
> out and warning the user if it detects them.  That's perfectly fine
> in my book.  It'll mean the code will work fine for the 90% of users
> and not confuse the other 10% to death.
> 
> That new dir-local editing facility could even allow you to
> use JSON notation to edit a variable's plist, and eglot.el could
> hint on that preference by setting 'serializer' and 'deserializer'
> properties on e-w-configuration (though a more lispy name would
> be 'write' and 'read' perhaps).
> 
> Additionally, in eglot.el, a variable watcher could be added to
> e-w-c to take care of LSP signalling automatically if changes to
> the value are detected.
> 
> So I urge you to generalize your code and propose it here
> in a new :core ELPA package.

Orthogonal to Augusto’s function, but I think something like this would be 
nice: a function that pops up a buffer and enters recursive edit for arbitrary 
input and edit, and when you hit C-c C-c, it returns the buffer content, kind 
of like Magit’s commit buffer. Plus buffer content validator (eg, validate 
JSON), and arbitrary major modes in the buffer, etc.

Load the file, and try

(json-parse-string
 (read-complex-value (lambda ()
                       (js-json-mode)
                       (read-complex-value-insert-prompt
                        "Type C-c C-c to finish, C-c C-k to abort:\n\n"))
                     (lambda ()
                       (condition-case nil
                           (progn (json-parse-buffer)
                                  t)
                         ((or end-of-file json-parse-error)
                          (message "Invalid JSON")
                          nil))))
 :object-type ‘plist)

It should pop a buffer in js-json-mode, and validates your JSON value. Typing 
C-c C-c returns the JSON as a plist.

Yuan

read-complex-value.el
Description: Binary data