[pitivi] undo: Report the current transaction when raising

[Alexandru Băluț <alexbalut src gnome org>]

commit c8bbfcdb496f1d16889cee869025ed44ff5ae1ff
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Sat Apr 9 23:55:40 2016 +0200

    undo: Report the current transaction when raising
    
    Differential Revision: https://phabricator.freedesktop.org/D901

 pitivi/undo/undo.py |   17 ++++++++++++-----
 1 files changed, 12 insertions(+), 5 deletions(-)
---
diff --git a/pitivi/undo/undo.py b/pitivi/undo/undo.py
index dd6eb84..cf38e2c 100644
--- a/pitivi/undo/undo.py
+++ b/pitivi/undo/undo.py
@@ -30,12 +30,16 @@ from pitivi.utils.loggable import Loggable
 
 
 class UndoError(Exception):
-    """ Any exception related to the undo/redo feature."""
+    """
+    Base class for undo/redo exceptions.
+    """
     pass
 
 
 class UndoWrongStateError(UndoError):
-    """ Exception related to the current state of the undo/redo stack. """
+    """
+    Exception related to the current state of the undo/redo stack.
+    """
     pass
 
 
@@ -92,6 +96,9 @@ class UndoableActionStack(UndoableAction):
         self.undone_actions = []
         self.finalizing_action = finalizing_action
 
+    def __repr__(self):
+        return "%s: %s" % (self.action_group_name, self.done_actions)
+
     def push(self, action):
         self.done_actions.append(action)
 
@@ -238,7 +245,7 @@ class UndoableActionLog(GObject.Object, Loggable):
         Undo the last recorded operation.
         """
         if self.stacks:
-            raise UndoWrongStateError("Recording a transaction")
+            raise UndoWrongStateError("Recording a transaction", self.stacks)
         if not self.undo_stacks:
             raise UndoWrongStateError("Nothing to undo")
 
@@ -252,7 +259,7 @@ class UndoableActionLog(GObject.Object, Loggable):
         Redo the last undone operation.
         """
         if self.stacks:
-            raise UndoWrongStateError("Recording a transaction")
+            raise UndoWrongStateError("Recording a transaction", self.stacks)
         if not self.redo_stacks:
             raise UndoWrongStateError("Nothing to redo")
 
@@ -266,7 +273,7 @@ class UndoableActionLog(GObject.Object, Loggable):
 
     def checkpoint(self):
         if self.stacks:
-            raise UndoWrongStateError("Recording a transaction")
+            raise UndoWrongStateError("Recording a transaction", self.stacks)
 
         self._checkpoint = self._takeSnapshot()