cider-toggle-buffer-connection fails

[alvinfrancis]

Expected behavior

cider-toggle-buffer-connection should toggle between CLJ and CLJS connections (if both exist) in a clojurec-mode buffer (e.g. cljc files) or in a cider-clojure-interaction-mode buffer (e.g. *cider-scratch*). This should allow expressions to be evaluated in the appropriate connection. Also, cider-connections should still contain both CLJ and CLJS connections after toggling.

Actual behavior

Connection to REPL is seemingly lost; evaluating expressions causes CIDER to complain that a Clojure REPL is required and that a jack in is probably needed. Also, cider-connections loses one of the connections (the current one).

Steps to reproduce the problem

1. Do lein new cider-toggle-buffer-connection
2. Edit project.clj to the following:

(defproject cider-toggle-buffer-connection "0.1.0-SNAPSHOT"
  :description "FIXME: write description"
  :url "http://example.com/FIXME"
  :license {:name "Eclipse Public License"
            :url "http://www.eclipse.org/legal/epl-v10.html"}
  :dependencies [[org.clojure/clojure "1.8.0"]
                 [com.cemerick/piggieback "0.2.1"]
                 [org.clojure/clojure "1.7.0"]]
  :repl-options {:nrepl-middleware [cemerick.piggieback/wrap-cljs-repl]}
  )

3. Do mv src/cider-toggle-buffer-connection/core.cljs src/cider-toggle-buffer-connection/core.cljc
4. Edit src/cider-toggle-buffer-connection/core.cljc to the following:

(ns cider-toggle-buffer-connection.core)
(println "Test")

5. Open src/cider-toggle-buffer-connection/core.cljc in emacs.
6. Do cider-jack-in-clojurescript.
7. Take note of the value of cider-connections: there should be two connections (CLJ and CLJS).
8. Evaluate (println "Test") with cider-eval-last-sexp. This should print "Test" in the *cider-repl cider-toggle-buffer-connection* buffer.
9. Do cider-toggle-buffer-connection.
10. Evaluate (println "Test") with cider-eval-last-sexp. This should cause CIDER to complain with the following message:

user-error: ‘cider-eval-last-sexp’ needs a Clojure REPL.
If you don’t know what that means, you probably need to jack-in (‘C-c M-j’).

11. Take note of the value of cider-connections: only the CLJS connections remains.

Environment & Version information

CIDER version information

;; CIDER 0.14.0 (Berlin), nREPL 0.2.12
;; Clojure 1.8.0, Java 1.8.0_74

Emacs version

GNU Emacs 25.1.3 (x86_64-apple-darwin15.6.0, Carbon Version 157 AppKit 1404.47) of 2016-09-18

Operating system

OSX 10.11.6

[alvinfrancis]

@dpsutton

[bbatsov]

@dpsutton did you end up looking into this?

[dpsutton]

Something to note: the reported behavior is not correct. When eval-ing code in a cljc buffer under cider-jack-in-clojurescript, the default behavior is to eval the code in both connection buffers. So the observed behavior from (println "Test") is that both repls print "Test". After toggling, you were stuck inside of only a single connection.

This happens because the toggling worked by setting a buffer local cider-connections to hide the regular list of connections. When grabbing the cider-other-connection, it did not consult the original list but the truncated list and was therefore unable to find the other connection.

Now the behavior is

1. eval -> "Test" in both buffers
2. toggle
3. eval -> "Test" in clj buffer
4. toggle
5. eval -> "Test" in cljs buffer
6. toggle with prefix
7. eval -> "Test" in both buffers