Added threading.defaultlocal

Author: hannes-ucsc

src/bd2k/util/threading.py

@@ -1,8 +1,8 @@
 from __future__ import absolute_import
-import logging
 import sys
 import threading
 
+
 class BoundedEmptySemaphore( threading._BoundedSemaphore ):
     """
     A bounded semaphore that is initially empty.
@@ -46,3 +46,20 @@ def join( self, *args, **kwargs ):
             type, value, traceback = self.exc_info
             self.exc_info = None
             raise type, value, traceback
+
+
+# noinspection PyPep8Naming
+class defaultlocal( threading.local ):
+    """
+    Thread local storage with default values for each field in each thread
+
+    >>> l = defaultlocal( foo=42 )
+    >>> def f(): print l.foo
+    >>> t = threading.Thread(target=f)
+    >>> t.start() ; t.join()
+    42
+    """
+
+    def __init__( self, **kwargs ):
+        super( defaultlocal, self ).__init__( )
+        self.__dict__.update( kwargs )