fix configurable observer

overviewer_core/settingsDefinition.py

@@ -46,6 +46,8 @@
 from settingsValidators import *
 import util
 from observer import ProgressBarObserver, LoggingObserver
+import platform
+import sys
 
 # renders is a dictionary mapping strings to dicts. These dicts describe the
 # configuration for that render. Therefore, the validator for 'renders' is set
@@ -96,6 +98,8 @@ processes = Setting(required=True, validator=int, default=-1)
 memcached_host = Setting(required=False, validator=str, default=None)
 
 if platform.system() == 'Windows' or not sys.stderr.isatty():
-    observer = LoggingObserver()
+    obs = LoggingObserver()
 else:
-    observer = ProgressBarObserver()
+    obs = ProgressBarObserver()
+
+observer = Setting(required=True, validator=validateObserver, default=obs)

overviewer_core/settingsValidators.py

@@ -182,6 +182,12 @@ def validateCrop(value):
         value[1],value[3] = value[3],value[1]
     return value
 
+def validateObserver(observer):
+    if all(map(lambda m: hasattr(observer, m), ['start', 'add', 'update', 'finish'])):
+        return observer
+    else:
+        raise ValidationException("%r does not look like an observer" % repr(observer))
+
 def make_dictValidator(keyvalidator, valuevalidator):
     """Compose and return a dict validator -- a validator that validates each
     key and value in a dictionary.