--- a/src/core/log.py	Mon May 05 20:12:21 2014 +0200
+++ b/src/core/log.py	Mon May 05 20:16:08 2014 +0200
@@ -373,17 +373,17 @@
 class ConfigureTwisted(ConfigureBasic):
     LOGGER_CLASS = TwistedLogger
 
-    def changeObserver(self, observer, can_color=False):
+    def changeObserver(self, observer, can_colors=False):
         """Install a hook on observer to manage SàT specificities
 
         @param observer: original observer to hook
-        @param can_color: True if observer can display ansi colors
+        @param can_colors: True if observer can display ansi colors
         """
         def observer_hook(event):
             """redirect non SàT log to twisted_logger, and add colors when possible"""
             if 'sat_logged' in event: # we only want our own logs, other are managed by twistedObserver
                 # we add colors if possible
-                if (can_color and self.LOGGER_CLASS.colors) or self.LOGGER_CLASS.force_colors:
+                if (can_colors and self.LOGGER_CLASS.colors) or self.LOGGER_CLASS.force_colors:
                     message = event.get('message', tuple())
                     level = event.get('level', C.LOG_LVL_INFO)
                     if message:
@@ -401,10 +401,10 @@
         log_obs = observer.__self__
         log_file = log_obs.write.__self__
         try:
-            can_color = log_file.isatty()
+            can_colors = log_file.isatty()
         except AttributeError:
-            can_color = False
-        return self.changeObserver(observer, can_color=can_color)
+            can_colors = False
+        return self.changeObserver(observer, can_colors=can_colors)
 
     def installObserverHook(self, observer):
         """Check observer type and install SàT hook when possible
@@ -417,7 +417,7 @@
             if isinstance(observer.__self__, self.log.FileLogObserver):
                 observer = self.changeFileLogObserver(observer)
             elif isinstance(observer.__self__, self.log.DefaultObserver):
-                observer = self.changeObserver(observer, can_color=True)
+                observer = self.changeObserver(observer, can_colors=True)
             else:
                 # we use print because log system is not fully initialized
                 print("Unmanaged observer [%s]" % observer)
@@ -551,21 +551,22 @@
 
     def configureFormat(self, fmt):
         import logging
-        format_ = fmt
 
         class SatFormatter(logging.Formatter):
             u"""Formatter which manage SàT specificities"""
+            _format = fmt
 
-            def __init__(self, fmt=None, datefmt=None):
-                super(SatFormatter, self).__init__(fmt, datefmt)
+            def __init__(self, can_colors=False):
+                super(SatFormatter, self).__init__(self._format)
+                self.can_colors = can_colors
 
             def format(self, record):
                 s = super(SatFormatter, self).format(record)
-                if self.with_color:
+                if self.with_colors and (self.can_colors or self.force_colors):
                     s = _ansiColors(record.levelname, s)
                 return s
 
-        self.formatter = SatFormatter(format_)
+        self.formatterClass = SatFormatter
 
     def configureOutput(self, output):
         self.manageOutputs(output)
@@ -574,13 +575,13 @@
         self.name_filter = FilterName(logger) if logger else None
 
     def configureColors(self, colors, force_colors):
-        import sys
-        self.formatter.with_color = colors & (sys.stdout.isatty() or force_colors)
+        self.formatterClass.with_colors = colors
+        self.formatterClass.force_colors = force_colors
         if not colors and force_colors:
             raise ValueError("force_colors can't be used if colors is False")
 
-    def _addHandler(self, root_logger, hdlr):
-        hdlr.setFormatter(self.formatter)
+    def _addHandler(self, root_logger, hdlr, can_colors=False):
+        hdlr.setFormatter(self.formatterClass(can_colors))
         root_logger.addHandler(hdlr)
         root_logger.setLevel(self.level)
         if self.name_filter is not None:
@@ -593,7 +594,11 @@
             for handler, options in _handlers.items():
                 if handler == C.LOG_OPT_OUTPUT_DEFAULT:
                     hdlr = logging.StreamHandler()
-                    self._addHandler(root_logger, hdlr)
+                    try:
+                        can_colors = hdlr.stream.isatty()
+                    except AttributeError:
+                        can_colors = False
+                    self._addHandler(root_logger, hdlr, can_colors=can_colors)
                 elif handler == C.LOG_OPT_OUTPUT_MEMORY:
                     from logging.handlers import BufferingHandler
                     class SatMemoryHandler(BufferingHandler):
@@ -601,12 +606,12 @@
                             super(SatMemoryHandler, self).emit(self.format(record))
                     hdlr = SatMemoryHandler(options)
                     _handlers[handler] = hdlr # we keep a reference to the handler to read the buffer later
-                    self._addHandler(root_logger, hdlr)
+                    self._addHandler(root_logger, hdlr, can_colors=False)
                 elif handler == C.LOG_OPT_OUTPUT_FILE:
                     import os.path
                     for path in options:
                         hdlr = logging.FileHandler(os.path.expanduser(path))
-                        self._addHandler(root_logger, hdlr)
+                        self._addHandler(root_logger, hdlr, can_colors=False)
                 else:
                     raise ValueError("Unknown handler type")
         else: