diff --git a/ein-shared-output.el b/ein-shared-output.el
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+;;; ein-shared-output.el --- Output buffer for ein-connect.el
+
+;; Copyright (C) 2012- Takafumi Arakaki
+
+;; Author: Takafumi Arakaki
+
+;; This file is NOT part of GNU Emacs.
+
+;; ein-shared-output.el is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; ein-shared-output.el is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with ein-shared-output.el.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; When executing code from outside of notebook, some place for output
+;; is needed.  This module buffer containing one special cell for that
+;; purpose.
+
+;;; Code:
+
+(eval-when-compile (require 'cl))
+(require 'eieio)
+
+(require 'ein-cell)
+
+(defclass ein:shared-output-cell (ein:codecell)
+  ((cell-type :initarg :cell-type :initform "shared-output")
+   ;; (element-names :initform (:prompt :output :footer))
+   )
+  "A singleton cell to show output from non-notebook buffers.")
+
+(defclass ein:$shared-output ()
+  ((cell :initarg :cell :type ein:shared-output-cell)
+   (ewoc :initarg :ewoc :type ewoc)))
+
+(defvar ein:@shared-output nil
+  "Hold an instance of `ein:$shared-output'.")
+
+(defconst ein:shared-output-buffer-name "*ein:shared-output*")
+
+
+(defun ein:shared-output-get-buffer ()
+  "Get the shared output buffer."
+  (get-buffer-create ein:shared-output-buffer-name))
+
+(defun ein:shared-output-get-or-create ()
+  (if ein:@shared-output
+      ein:@shared-output
+    (with-current-buffer (ein:shared-output-get-buffer)
+      ;; FIXME: This is a duplication of `ein:notebook-from-json'.
+      ;;        Must be merged.
+      (let* ((inhibit-read-only t)
+             ;; Enable nonsep for ewoc object (the last argument is non-nil).
+             ;; This is for putting read-only text properties to the newlines.
+             ;; FIXME: Do not depend on `ein:notebook-pp'!
+             (ewoc (ewoc-create 'ein:notebook-pp
+                                (ein:propertize-read-only "\n")
+                                nil t))
+             (cell (ein:shared-output-cell "SharedOutputCell"
+                                           :ewoc ewoc)))
+        (erase-buffer)
+        (setq ein:@shared-output
+              (ein:$shared-output "SharedOutput" :ewoc ewoc :cell cell))
+        (ein:cell-enter-last cell))
+      ein:@shared-output)))
+
+(defun ein:shared-output-get-cell ()
+  "Get the singleton shared output cell.
+Create a cell if the buffer has none."
+  (oref (ein:shared-output-get-or-create) :cell))
+
+(defun ein:shared-output-pop-to-buffer ()
+  (interactive)
+  (ein:shared-output-get-or-create)
+  (pop-to-buffer (ein:shared-output-get-buffer)))
+
+(provide 'ein-shared-output)
+
+;;; ein-shared-output.el ends here