Refactor: loading of components now done in a seperate module + better error reporting

homeassistant/__init__.py

@@ -61,24 +61,11 @@ class HomeAssistant(object):
         self.services = ServiceRegistry(self.bus, pool)
         self.states = StateMachine(self.bus)
 
-        self._config_dir = os.getcwd()
+        self.config_dir = os.getcwd()
 
-    @property
+    def get_config_path(self, path):
-    def config_dir(self):
-        """ Return value of config dir. """
-        return self._config_dir
-
-    @config_dir.setter
-    def config_dir(self, value):
-        """ Update value of config dir and ensures it's in Python path. """
-        self._config_dir = value
-
-        # Ensure we can load components from the config dir
-        sys.path.append(value)
-
-    def get_config_path(self, sub_path):
         """ Returns path to the file within the config dir. """
-        return os.path.join(self._config_dir, sub_path)
+        return os.path.join(self.config_dir, path)
 
     def start(self):
         """ Start home assistant. """

homeassistant/bootstrap.py

@@ -1,4 +1,6 @@
 """
+homeassistant.bootstrap
+~~~~~~~~~~~~~~~~~~~~~~~
 Provides methods to bootstrap a home assistant instance.
 
 Each method will return a tuple (bus, statemachine).
@@ -14,6 +16,7 @@ from collections import defaultdict
 from itertools import chain
 
 import homeassistant
+import homeassistant.loader as loader
 import homeassistant.components as core_components
 import homeassistant.components.group as group
 
@@ -46,11 +49,13 @@ def from_config_dict(config, hass=None):
     # List of components we are going to load
     to_load = [key for key in config.keys() if key != homeassistant.DOMAIN]
 
+    loader.prepare(hass)
+
     # Load required components
     while to_load:
         domain = to_load.pop()
 
-        component = core_components.get_component(domain, logger)
+        component = loader.get_component(domain)
 
         # if None it does not exist, error already thrown by get_component
         if component is not None:
@@ -123,7 +128,7 @@ def from_config_dict(config, hass=None):
 
         if group.DOMAIN not in components:
             components[group.DOMAIN] = \
-                core_components.get_component(group.DOMAIN, logger)
+                loader.get_component(group.DOMAIN)
 
     # Setup the components
     if core_components.setup(hass, config):

homeassistant/components/__init__.py

@@ -20,6 +20,7 @@ import importlib
 
 import homeassistant as ha
 import homeassistant.util as util
+from homeassistant.loader import get_component
 
 # Contains one string or a list of strings, each being an entity id
 ATTR_ENTITY_ID = 'entity_id'
@@ -47,80 +48,14 @@ SERVICE_MEDIA_PAUSE = "media_pause"
 SERVICE_MEDIA_NEXT_TRACK = "media_next_track"
 SERVICE_MEDIA_PREV_TRACK = "media_prev_track"
 
-_COMPONENT_CACHE = {}
+__LOGGER = logging.getLogger(__name__)
-
-
-def get_component(comp_name, logger=None):
-    """ Tries to load specified component.
-        Looks in config dir first, then built-in components.
-        Only returns it if also found to be valid. """
-
-    if comp_name in _COMPONENT_CACHE:
-        return _COMPONENT_CACHE[comp_name]
-
-    # First config dir, then built-in
-    potential_paths = ['custom_components.{}'.format(comp_name),
-                       'homeassistant.components.{}'.format(comp_name)]
-
-    for path in potential_paths:
-        comp = _get_component(path, logger)
-
-        if comp is not None:
-            if logger is not None:
-                logger.info("Loaded component {} from {}".format(
-                    comp_name, path))
-
-            _COMPONENT_CACHE[comp_name] = comp
-
-            return comp
-
-    # We did not find a component
-    if logger is not None:
-        logger.error(
-            "Failed to find component {}".format(comp_name))
-
-    return None
-
-
-def _get_component(module, logger):
-    """ Tries to load specified component.
-        Only returns it if also found to be valid."""
-    try:
-        comp = importlib.import_module(module)
-
-    except ImportError:
-        return None
-
-    # Validation if component has required methods and attributes
-    errors = []
-
-    if not hasattr(comp, 'DOMAIN'):
-        errors.append("Missing DOMAIN attribute")
-
-    if not hasattr(comp, 'DEPENDENCIES'):
-        errors.append("Missing DEPENDENCIES attribute")
-
-    if not hasattr(comp, 'setup'):
-        errors.append("Missing setup method")
-
-    if errors:
-        if logger:
-            logger.error("Found invalid component {}: {}".format(
-                module, ", ".join(errors)))
-
-        return None
-
-    else:
-        return comp
 
 
 def is_on(hass, entity_id=None):
     """ Loads up the module to call the is_on method.
     If there is no entity id given we will check all. """
-    logger = logging.getLogger(__name__)
-
     if entity_id:
-        group = get_component('group', logger)
+        group = get_component('group')
 
         entity_ids = group.expand_entity_ids([entity_id])
     else:
@@ -129,7 +64,7 @@ def is_on(hass, entity_id=None):
     for entity_id in entity_ids:
         domain = util.split_entity_id(entity_id)[0]
 
-        module = get_component(domain, logger)
+        module = get_component(domain)
 
         try:
             if module.is_on(hass, entity_id):

homeassistant/components/demo.py

@@ -7,10 +7,10 @@ Sets up a demo environment that mimics interaction with devices
 import random
 
 import homeassistant as ha
-import homeassistant.components.group as group
+import homeassistant.loader as loader
 from homeassistant.components import (SERVICE_TURN_ON, SERVICE_TURN_OFF,
                                       STATE_ON, STATE_OFF, ATTR_ENTITY_PICTURE,
-                                      get_component, extract_entity_ids)
+                                      extract_entity_ids)
 from homeassistant.components.light import (ATTR_XY_COLOR, ATTR_BRIGHTNESS,
                                             GROUP_NAME_ALL_LIGHTS)
 from homeassistant.util import split_entity_id
@@ -22,6 +22,7 @@ DEPENDENCIES = []
 
 def setup(hass, config):
     """ Setup a demo environment. """
+    group = loader.get_component('group')
 
     if config[DOMAIN].get('hide_demo_state') != '1':
         hass.states.set('a.Demo_Mode', 'Enabled')
@@ -57,7 +58,7 @@ def setup(hass, config):
     if ha.CONF_LONGITUDE not in config[ha.DOMAIN]:
         config[ha.DOMAIN][ha.CONF_LONGITUDE] = '-117.22743'
 
-    get_component('sun').setup(hass, config)
+    loader.get_component('sun').setup(hass, config)
 
     # Setup fake lights
     lights = ['light.Bowl', 'light.Ceiling', 'light.TV_Back_light',

homeassistant/loader.py

@@ -0,0 +1,107 @@
+"""
+homeassistant.loader
+~~~~~~~~~~~~~~~~~~~~
+
+Provides methods for loading Home Assistant components.
+"""
+import sys
+import pkgutil
+import importlib
+import logging
+
+# List of available components
+AVAILABLE_COMPONENTS = []
+
+# Dict of loaded components mapped name => module
+_COMPONENT_CACHE = {}
+
+_LOGGER = logging.getLogger(__name__)
+
+
+def prepare(hass):
+    """ Prepares the loading of components. """
+    # Ensure we can load custom components from the config dir
+    sys.path.append(hass.config_dir)
+
+    # pylint: disable=import-error
+    import custom_components
+    import homeassistant.components as components
+
+    AVAILABLE_COMPONENTS.clear()
+
+    AVAILABLE_COMPONENTS.extend(
+        item[1] for item in
+        pkgutil.iter_modules(components.__path__, 'homeassistant.components.'))
+
+    AVAILABLE_COMPONENTS.extend(
+        item[1] for item in
+        pkgutil.iter_modules(custom_components.__path__, 'custom_components.'))
+
+
+def get_component(comp_name):
+    """ Tries to load specified component.
+        Looks in config dir first, then built-in components.
+        Only returns it if also found to be valid. """
+
+    if comp_name in _COMPONENT_CACHE:
+        return _COMPONENT_CACHE[comp_name]
+
+    # First check config dir, then built-in
+    potential_paths = [path for path in
+                       ['custom_components.{}'.format(comp_name),
+                        'homeassistant.components.{}'.format(comp_name)]
+                       if path in AVAILABLE_COMPONENTS]
+
+    if not potential_paths:
+        _LOGGER.error("Failed to find component {}".format(comp_name))
+
+        return None
+
+    for path in potential_paths:
+        comp = _get_component(path)
+
+        if comp is not None:
+            _LOGGER.info("Loaded component {} from {}".format(
+                comp_name, path))
+
+            _COMPONENT_CACHE[comp_name] = comp
+
+            return comp
+
+    # We did find components but were unable to load them
+    _LOGGER.error("Unable to load component {}".format(comp_name))
+
+    return None
+
+
+def _get_component(module):
+    """ Tries to load specified component.
+        Only returns it if also found to be valid."""
+    try:
+        comp = importlib.import_module(module)
+
+    except ImportError:
+        _LOGGER.exception("Error loading {}".format(module))
+
+        return None
+
+    # Validation if component has required methods and attributes
+    errors = []
+
+    if not hasattr(comp, 'DOMAIN'):
+        errors.append("missing DOMAIN attribute")
+
+    if not hasattr(comp, 'DEPENDENCIES'):
+        errors.append("missing DEPENDENCIES attribute")
+
+    if not hasattr(comp, 'setup'):
+        errors.append("missing setup method")
+
+    if errors:
+        _LOGGER.error("Found invalid component {}: {}".format(
+            module, ", ".join(errors)))
+
+        return None
+
+    else:
+        return comp