Merge branch 'feature/ghi-#5-dispatcher' into develop

snowsaw/dispatcher.py

@@ -0,0 +1,64 @@
+import os
+from .plugin import Plugin
+from .logging import Logger
+from .context import Context
+
+
+class Dispatcher(object):
+ """
+ Dispatches tasks to loaded plugins.
+ """
+ def __init__(self, snowblock_dir):
+ self._log = Logger()
+ self._setup_context(snowblock_dir)
+ self._load_plugins()
+
+ def _setup_context(self, snowblock_dir):
+ """
+ Sets up the plugin context for the specified snowblock.
+
+ :param snowblock_dir: The directory of the snowblock
+ :return: The plugin context
+ """
+ path = os.path.abspath(os.path.realpath(os.path.expanduser(snowblock_dir)))
+ if not os.path.exists(path):
+ raise DispatchError("Nonexistent snowblock directory")
+ self._context = Context(path)
+
+ def dispatch(self, tasks):
+ """
+ Dispatches the specified tasks to the loaded plugins.
+
+ :param tasks: The tasks to dispatch
+ :return: True if all tasks have been handled by the loaded plugins successfully, False otherwise
+ """
+ success = True
+ for task in tasks:
+ for action in task:
+ handled = False
+ if action == "defaults":
+ self._context.set_defaults(task[action])
+ handled = True
+ for plugin in self._plugins:
+ if plugin.can_handle(action):
+ try:
+ success &= plugin.handle(action, task[action])
+ handled = True
+ except Exception:
+ self._log.error("An error was encountered while executing action \"{}\"".format(action))
+ if not handled:
+ success = False
+ self._log.error("Action \"{}\" not handled".format(action))
+ return success
+
+ def _load_plugins(self):
+ """
+ Loads all found plugins.
+
+ :return: None
+ """
+ self._plugins = [plugin(self._context) for plugin in Plugin.__subclasses__()]
+
+
+class DispatchError(Exception):
+ pass