Change the error type raised by Clipboard.synchronized_changes()

Re: dictation-toolbox#390.

TimeoutError is now used, as in the PR.  An exception class with that
name has been introduced for Python 2 in dragonfly.error for compati-
bility reasons.

Author: drmfinlay

dragonfly/__init__.py

@@ -25,6 +25,8 @@
 #---------------------------------------------------------------------------
 from .config            import Config, Section, Item
 from .error             import DragonflyError, GrammarError
+if sys.version_info[0] == 2:  # Don't override the Python 3 class.
+    from .error         import TimeoutError
 
 #---------------------------------------------------------------------------
 from .engines           import (get_engine, EngineError, MimicFailure,

dragonfly/error.py

@@ -24,5 +24,11 @@ class DragonflyError(Exception):
     pass
 
 
+# Used by the clipboard classes in Python 2.
+# Python 3 has its own TimeoutError class.
+class TimeoutError(Exception):
+    pass
+
+
 class GrammarError(Exception):
     pass

dragonfly/windows/base_clipboard.py

@@ -33,7 +33,11 @@
 import re
 import time
 
-from six import text_type, binary_type, integer_types
+from six import PY2, text_type, binary_type, integer_types
+
+# Import our TimeoutError substitute for Python 2, needed below.
+if PY2:
+    from dragonfly.error import TimeoutError
 
 
 #===========================================================================
@@ -163,7 +167,7 @@ def synchronized_changes(cls, timeout, step=0.001, formats=None,
         """
             Context manager for synchronizing local and system clipboard
             changes.  This takes the same arguments as the
-            :meth:`wait_for_change` method.  A ``RuntimeError`` is raised if
+            :meth:`wait_for_change` method.  A ``TimeoutError`` is raised if
             the system clipboard does not change.
 
             Arguments:
@@ -204,7 +208,7 @@ def synchronized_changes(cls, timeout, step=0.001, formats=None,
                                           initial_clipboard)
             if not changed:
                 message = "Timed out waiting for clipboard to change"
-                raise RuntimeError(message)
+                raise TimeoutError(message)
 
     #-----------------------------------------------------------------------
 

dragonfly/windows/win32_clipboard.py

@@ -34,14 +34,19 @@
 import threading
 import time
 
-from six                              import integer_types, reraise
+from six                              import PY2, integer_types, reraise
 
 import pywintypes
 import win32clipboard
 import win32con
 
 from dragonfly.windows.base_clipboard import BaseClipboard
 
+# Import our TimeoutError substitute for Python 2, needed below.
+if PY2:
+    from dragonfly.error import TimeoutError
+
+
 #===========================================================================
 
 class win32_clipboard_ctx(object):
@@ -231,7 +236,7 @@ def synchronized_changes(cls, timeout, step=0.001, formats=None,
                                            initial_clipboard, seq_no)
             if not changed:
                 message = "Timed out waiting for clipboard to change"
-                raise RuntimeError(message)
+                raise TimeoutError(message)
 
     #-----------------------------------------------------------------------