Add elpy-shell-set-local-shell function

elpy-shell.el

@@ -350,7 +350,38 @@ if ARG is negative or 0, disable the use of a dedicated shell."
     (if (<= arg 0)
         (kill-local-variable 'python-shell-buffer-name)
       (setq-local python-shell-buffer-name
-                  (format "Python[%s]" (buffer-name))))))
+                  (format "Python[%s]L" (buffer-name))))))
+
+(defun elpy-shell-set-local-shell (&optional shell-name)
+  ;; Todo: doc need rewriting
+  "Associate the current buffer to a given shell.
+
+This means that the code from the current buffer will be sent to this shell.
+
+If SHELL-NAME is not specified, ask with completion for a name.
+
+If SHELL-NAME is \"Global\", associate the current buffer to the main python
+shell (often \"*Python*\" shell)."
+  (interactive)
+  (let* ((current-shell-name (if (local-variable-p 'python-shell-buffer-name)
+                                 (progn
+                                   (string-match "Python\\[\\(.*?\\)\\]"
+                                                 python-shell-buffer-name)
+                                   (match-string 1 python-shell-buffer-name))
+                               "Global"))
+         (shell-names (cl-loop
+                for buffer in (buffer-list)
+                for buffer-name = (substring-no-properties (buffer-name buffer))
+                if (string-match "\\*Python\\[\\(.*?\\)\\]\\*" buffer-name)
+                collect (match-string 1 buffer-name)))
+         (candidates (remove current-shell-name
+                          (delete-dups
+                           (append (list (buffer-name) "Global") shell-names))))
+         (prompt (format "Shell name (current: %s): " current-shell-name))
+         (shell-name (or shell-name (completing-read prompt candidates))))
+    (if (string= shell-name "Global")
+       (kill-local-variable 'python-shell-buffer-name)
+      (setq-local python-shell-buffer-name (format "Python[%s]" shell-name)))))
 
 (defun elpy-shell-change-global-shell-name (name)
   "Tell Elpy to use another python shell named NAME.