config: Restructure config loading to allow defaults.

[matthijs/projects/backupninja.git] / src / lib / backupninja / handlers / __init__.py

diff --git a/src/lib/backupninja/handlers/__init__.py b/src/lib/backupninja/handlers/__init__.py
index da07b6d495146a615e29ca4c8a22b807d8de39bb..ccb5c8c142ec1b8b9fd0dca30df8d71ed7d8b311 100644 (file)
--- a/src/lib/backupninja/handlers/__init__.py
+++ b/src/lib/backupninja/handlers/__init__.py
@@ -22,60 +22,71 @@
 import sys
 import logging as log
 
+from backupninja import config
+
 class Handler(object):
-    def __init__(self, conf):
-        self.conf = conf
+    def __init__(self):
+        # Subclasses should overwrite this with their default config
+        # See backupninja.config.load_config for the structure of this
+        # value.
+        self.default_config = {}
 
-    def run(self):
+    def run(self, **kwargs):
         """
         Run this handler for a single target. Override this method
         in a subclass
         """
         pass
 
-    def finish(self):
+    def finish(self, **kwargs):
         """
         Called when all targets have been processed. Can be overridden
         in a subclass.
         """
         pass
 
-def create_handler(ty, conf):
+    def load_config(self, filename):
+        """
+        Load the configuration for this action from the given filename.
+        """
+        self.conf = config.load_config(filename, self.default_config)
+
+        
+
+def create_handler(ty):
     """
     Create a new (subclass of) Handler object for an action with the
-    given type. conf is the configuration to pass to the handler.
+    given type.
 
-    If the handler cannot be loaded, it is logged and None is returned
-    (but any exceptions raised by the handler code itself are not
-    handled).
+    If the handler cannot be loaded, an exception is thrown.
     """
     modname = 'backupninja.handlers.%s' % ty
     # Load the handler if it is not loaded yet
     if not modname in sys.modules:
+        log.debug('Loading handler for type "%s"', ty)
         try:
             __import__(modname, globals(), locals(), [])
         except ImportError, e:
-            log.error('Cannot load action handler for "%s": %s'
-                     , ty, e)
-            return None
+            # Add some extra info, since the default exception does not
+            # show the full module name.
+            raise ImportError('Cannot load module %s: %s' % (modname, e))
+        log.debug('Loaded handler for type "%s" from "%s"', ty, sys.modules[modname].__file__)
     # Get the module from the module table
     module = sys.modules[modname]
 
     # Check that the module has a "handler" top level function, which
     # should create a new Handler object.
     if not hasattr(module, 'handler'):
-        log.error('Action handler for "%s" (in "%s) is not valid: it '
-                  'does not have a "handler" top level function.'
-                 , ty, module.__file__)
-        return None
+        raise ImportError('%s is not valid: it '
+                          'does not have a "handler" top level function.' 
+                          % (module.__file__))
 
     # Call the "handler" function to create the actual handler
-    handler = module.handler(conf)
+    handler = module.handler()
    
     # Check if the handler returned is really a subclass of Handler
     if not isinstance(handler, Handler):
-        log.error('Action handler for "%s" (in "%s) is not valid: it '
-                  'does not return a subclass of backupninja.handlers.Handler.'
-                 , ty, module.__file__)
-        return None
+        raise TypeError('%s is not valid, %s.handler did not return a '
+                        'subclass of backupninja.handlers.Handler.'
+                        % (module.__file__, modname))
     return handler