Adds an option to disable eldoc (#197)

Eldoc is quite nice and puts the function signatures in the
minibuffer. But it does this at a cost. Since inf-clojure only uses a
single connection (currently at least) the commands interrupt the
values of `*1`, `*2`, etc. Further, this can lead to multiple prompts
appearing in the repl buffer.

```clojure
user=> user=> (map inc (range 4))
(1 2 3 4)
user=> user=> *1
nil
user=>
```

`user` appears multiple times, and then `*1` has been bound to the
result of getting arglists.

```clojure
user=> (+ 1 1)
2
user=> *1
([f] [f coll] [f c1 c2] [f c1 c2 c3] [f c1 c2 c3 & colls])
```

The multiple prompts is quite annoying when inserting forms into the
repl.

Author: dpsutton

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## master (unreleased)
 
+### New features
+
+* [#187](https://github.com/clojure-emacs/inf-clojure/pull/197): Defcustom `inf-clojure-enable-eldoc` to disable eldoc interaction.
+
 ## 3.1.0 (2021-07-23)
 
 ### New features

README.md

@@ -356,18 +356,20 @@ startup when using the `inf-clojure` command or is specified manually when using
 
 #### ElDoc
 
-**Note:** You can skip this section if you're using Emacs 26.1+, as `eldoc-mode`
-is enabled by default there.
-
 `eldoc-mode` is supported in Clojure source buffers and `*inferior-clojure*`
 buffers which are running a Clojure REPL.
 
-When ElDoc is enabled and there is an active REPL, it will show the
-argument list of the function call you are currently editing in the
-echo area.
+When ElDoc is enabled and there is an active REPL, it will show the argument
+list of the function call you are currently editing in the echo area. It
+accomplishes this by evaluating forms to get the metadata for the vars under
+your cursor. One side effect of this is that it can mess with repl vars like
+`*1` and `*2`. You can disable inf-clojure's Eldoc functionality with `(setq
+inf-clojure-enable-eldoc nil)`.
+
 
-You can activate ElDoc with `M-x eldoc-mode` or by adding the
-following to you Emacs config:
+ElDoc should be enabled by default in Emacs 26.1+. If it is not active by
+default, you can activate ElDoc with `M-x eldoc-mode` or by adding the following
+to you Emacs config:
 
 ```emacs-lisp
 (add-hook 'clojure-mode-hook #'eldoc-mode)

inf-clojure.el

@@ -420,6 +420,13 @@ mode line entirely."
   :type 'sexp
   :risky t)
 
+(defcustom inf-clojure-enable-eldoc t
+  "Var that allows disabling `eldoc-mode` in `inf-clojure`.
+
+Set to `nil` to disable eldoc.  Eldoc can be quite useful by
+displaying function signatures in the modeline, but can also
+cause multiple prompts to appear and mess with `*1`, `*2`, etc.")
+
 ;;;###autoload
 (define-minor-mode inf-clojure-minor-mode
   "Minor mode for interacting with the inferior Clojure process buffer.
@@ -430,7 +437,8 @@ The following commands are available:
   :lighter inf-clojure-mode-line
   :keymap inf-clojure-minor-mode-map
   (setq-local comint-input-sender 'inf-clojure--send-string)
-  (inf-clojure-eldoc-setup)
+  (when inf-clojure-enable-eldoc
+    (inf-clojure-eldoc-setup))
   (make-local-variable 'completion-at-point-functions)
   (add-to-list 'completion-at-point-functions
                #'inf-clojure-completion-at-point))
@@ -632,7 +640,8 @@ to continue it."
   (setq mode-line-process '(":%s"))
   (clojure-mode-variables)
   (clojure-font-lock-setup)
-  (inf-clojure-eldoc-setup)
+  (when inf-clojure-enable-eldoc
+    (inf-clojure-eldoc-setup))
   (setq comint-get-old-input #'inf-clojure-get-old-input)
   (setq comint-input-filter #'inf-clojure-input-filter)
   (setq-local comint-prompt-read-only inf-clojure-prompt-read-only)
@@ -1408,6 +1417,7 @@ Return the number of nested sexp the point was over or after."
   "Backend function for eldoc to show argument list in the echo area."
   ;; todo: this never gets unset once connected and is a lie
   (when (and (inf-clojure-connected-p)
+             inf-clojure-enable-eldoc
              ;; don't clobber an error message in the minibuffer
              (not (member last-command '(next-error previous-error))))
     (let* ((info (inf-clojure-eldoc-info-in-current-sexp))