Add a FingersCrossedHandler that does not forward records until a war…

…ning or higher occurs.

logbook/more.py

@@ -0,0 +1,38 @@
+# -*- coding: utf-8 -*-
+"""
+    logbook.more
+    ~~~~~~~~~~~~
+
+    Fancy stuff for logbook.
+
+    :copyright: (c) 2010 by Armin Ronacher, Georg Brandl.
+    :license: BSD, see LICENSE for more details.
+"""
+
+from logbook.base import Logger, NOTSET, WARNING
+from logbook.handlers import Handler
+
+
+class FingersCrossedHandler(Handler):
+    def __init__(self, handler, action_level=WARNING):
+        Handler.__init__(self)
+        self._level = action_level
+        self._handler = handler
+        self._records = []
+        self._seen_error = False
+
+    def contextbound(self, processor=None, bubble=True):
+        del self._records[:]
+        self._seen_error = False
+        return Handler.contextbound(self, processor, bubble)
+
+    def emit(self, record):
+        if self._seen_error:
+            return self._handler.emit(record)
+        elif record.level >= self._level:
+            for old_record in self._records:
+                self._handler.emit(old_record)
+            self._handler.emit(record)
+            self._seen_error = True
+        else:
+            self._records.append(record)

test_logbook.py

@@ -9,7 +9,6 @@
 import string
 from random import randrange
 from calendar import timegm
-from time import mktime
 from itertools import izip
 from contextlib import contextmanager
 from cStringIO import StringIO
@@ -327,5 +326,30 @@ def test_basic_compat(self):
                          in captured.getvalue())
 
 
+class MoreTestCase(LogbookTestCase):
+
+    def test_fingerscrossed(self):
+        from logbook.more import FingersCrossedHandler
+
+        orig_handler = logbook.handlers.StderrHandler()
+        handler = FingersCrossedHandler(orig_handler, logbook.WARNING)
+
+        # if no warning occurs, the infos are not logged
+        with handler.contextbound(bubble=False):
+            with capture_stderr() as captured:
+                self.log.info('some info')
+            self.assertEquals(captured.getvalue(), '')
+
+        # but if it does, all log messages are output
+        with handler.contextbound(bubble=False):
+            with capture_stderr() as captured:
+                self.log.info('some info')
+                self.log.warning('something happened')
+            logs = captured.getvalue()
+            self.assert_('some info' in logs)
+            self.assert_('something happened' in logs)
+
+
+
 if __name__ == '__main__':
     unittest.main()