7097: add UndoableStyledBuffer.undo_disabled

Refactoring away the coupling between Spell and StyleTextEditor
innards:

1) add a context manager UndoableStyledBuffer.undo_disabled
2) add a forwarding to it as StyleTextEditor.undo_disabled
3) use that in Spell.__real_set_active_spellcheck

gramps/gui/spell.py

@@ -2,6 +2,7 @@
 # Gramps - a GTK+/GNOME based genealogy program
 #
 # Copyright (C) 2005-2006  Donald N. Allingham
+# Copyright (C) 2014       Vassilii Khachaturov
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -128,9 +129,8 @@ class Spell(object):
                             #other installed one will also be available
                             self.gtkspell_spell.set_language("en")
                             #if that fails no spellchecker will be available
-                    self.textview.textbuffer.not_undoable_action = True
-                    success = self.gtkspell_spell.attach(self.textview)
-                    self.textview.textbuffer.not_undoable_action = False
+                    with self.textview.undo_disabled():
+                        success = self.gtkspell_spell.attach(self.textview)
                     try:
                         #show decoded language codes in the context menu
                         #requires the iso-codes package from  http://pkg-isocodes.alioth.debian.org

gramps/gui/widgets/styledtexteditor.py

@@ -177,6 +177,7 @@ class StyledTextEditor(Gtk.TextView):
     def __init__(self):
         """Setup initial instance variable values."""
         self.textbuffer = UndoableStyledBuffer()
+        self.undo_disabled = self.textbuffer.undo_disabled # see bug 7097
         self.textbuffer.connect('style-changed', self._on_buffer_style_changed)
         self.textbuffer.connect('changed', self._on_buffer_changed)
         GObject.GObject.__init__(self, buffer=self.textbuffer)

gramps/gui/widgets/undoablestyledbuffer.py

@@ -3,7 +3,8 @@
 #
 # Copyright (C) 2009  Florian Heinle
 # Copyright (C) 2010  Doug Blank <doug.blank@gmail.com>
-# Copyright (C) 2010       Benny Malengier
+# Copyright (C) 2010  Benny Malengier
+# Copyright (C) 2014  Vassilii Khachaturov
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -20,14 +21,14 @@
 # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 #
 
-# $Id$
-
 """ 
 gtk textbuffer with undo functionality 
 """
 
 __all__ = ["UndoableStyledBuffer"]
 
+from contextlib import contextmanager
+
 from gi.repository import Gtk
 
 from gramps.gen.lib.styledtext import StyledText
@@ -79,6 +80,25 @@ class UndoableStyledBuffer(StyledTextBuffer):
         self.connect('apply-tag', self.on_tag_insert_undoable)
         self.connect_after('apply-tag', self.on_tag_afterinsert_undoable)
 
+    @contextmanager
+    def undo_disabled(self):
+        """
+        Assures that not_undoable_action is False during the context.
+
+        Usage example (see gramps/gui/widgets/styledtexteditor.py)::
+        
+            with self.buffer.undo_disabled():
+                ... # heavy stuff like spell checking
+        """
+        oldflag = self.not_undoable_action 
+        self.not_undoable_action = True
+        try:
+            yield
+        except:
+            raise
+        finally:
+            self.not_undoable_action = oldflag
+
     def on_tag_insert_undoable(self, buffer, tag, start, end):
         if not self.undo_in_progress:
             self._empty_redo_stack()