Added wrapper handler

docs/api/handlers.rst

@@ -57,6 +57,9 @@ Core Handlers
 .. autoclass:: NullHandler
    :members:
 
+.. autoclass:: WrapperHandler
+   :members:
+
 .. autofunction:: create_syshandler
 
 Mixin Classes

logbook/__init__.py

@@ -17,7 +17,8 @@
      MonitoringFileHandler, StderrHandler, RotatingFileHandler, \
      TimedRotatingFileHandler, TestHandler, MailHandler, SyslogHandler, \
      NullHandler, NTEventLogHandler, create_syshandler, StringFormatter, \
-     StringFormatterHandlerMixin, HashingHandlerMixin, LimitingHandlerMixin
+     StringFormatterHandlerMixin, HashingHandlerMixin, \
+     LimitingHandlerMixin, WrapperHandler
 
 
 # create an anonymous default logger and provide all important

logbook/handlers.py

@@ -243,6 +243,32 @@ class NullHandler(Handler):
     blackhole = True
 
 
+class WrapperHandler(Handler):
+    """A class that can wrap another handler and redirect all calls to the
+    wrapped handler::
+
+        handler = WrapperHandler(other_handler)
+
+    Subclasses should override the :attr:`_direct_attrs` attribute as
+    necessary.
+    """
+
+    #: a set of direct attributes that are not forwarded to the inner
+    #: handler.  This has to be extended as necessary.
+    _direct_attrs = frozenset(['handler'])
+
+    def __init__(self, handler):
+        self.handler = handler
+
+    def __getattr__(self, name):
+        return getattr(self.handler, name)
+
+    def __setattr__(self, name, value):
+        if name in self._direct_attrs:
+            return Handler.__setattr__(self, name, value)
+        setattr(self.handler, name, value)
+
+
 class StringFormatter(object):
     """Many handlers format the log entries to text format.  This is done
     by a callable that is passed a log record and returns an unicode

logbook/queues.py

@@ -12,7 +12,7 @@
 from Queue import Empty, Queue as ThreadQueue
 from itertools import cycle
 from logbook.base import NOTSET, LogRecord, dispatch_record
-from logbook.handlers import Handler
+from logbook.handlers import Handler, WrapperHandler
 from logbook.helpers import json
 
 
@@ -363,7 +363,7 @@ def _target(self):
             self.wrapper_handler.handler.emit(record)
 
 
-class ThreadedWrapperHandler(Handler):
+class ThreadedWrapperHandler(WrapperHandler):
     """This handled uses a single background thread to dispatch log records
     to a specific other handler using an internal queue.  The idea is that if
     you are using a handler that requires some time to hand off the log records
@@ -382,19 +382,11 @@ class ThreadedWrapperHandler(Handler):
     _direct_attrs = frozenset(['handler', 'queue', 'controller'])
 
     def __init__(self, handler):
-        self.handler = handler
+        WrapperHandler.__init__(self, handler)
         self.queue = ThreadQueue(-1)
         self.controller = TWHThreadController(self)
         self.controller.start()
 
-    def __getattr__(self, name):
-        return getattr(self.handler, name)
-
-    def __setattr__(self, name, value):
-        if name in self._direct_attrs:
-            return Handler.__setattr__(self, name, value)
-        setattr(self.handler, name, value)
-
     def close(self):
         self.controller.stop()
         self.handler.close()