Allow platforms to specify dependencies

homeassistant/bootstrap.py

@@ -30,6 +30,8 @@
 
 ATTR_COMPONENT = "component"
 
+PLATFORM_FORMAT = '{}.{}'
+
 
 def setup_component(hass, domain, config=None):
     """ Setup a component and all its dependencies. """
@@ -95,6 +97,35 @@ def _setup_component(hass, domain, config):
     return False
 
 
+def prepare_setup_platform(hass, config, domain, platform_name):
+    """ Loads a platform and makes sure dependencies are setup. """
+    _ensure_loader_prepared(hass)
+
+    platform_path = PLATFORM_FORMAT.format(domain, platform_name)
+
+    platform = loader.get_component(platform_path)
+
+    # Not found
+    if platform is None:
+        _LOGGER.error('Unable to find platform %s', platform_path)
+        return None
+
+    # Already loaded or no dependencies
+    elif (platform_path in hass.config.components or
+          not hasattr(platform, 'DEPENDENCIES')):
+        return platform
+
+    # Load dependencies
+    for component in platform.DEPENDENCIES:
+        if not setup_component(hass, component, config):
+            _LOGGER.error(
+                'Unable to prepare setup for platform %s because not all '
+                'dependencies could be initialized', platform_path)
+            return None
+
+    return platform
+
+
 # pylint: disable=too-many-branches, too-many-statements
 def from_config_dict(config, hass=None):
     """

homeassistant/helpers/entity_component.py

@@ -4,7 +4,7 @@
 
 Provides helpers for components that manage entities.
 """
-from homeassistant.loader import get_component
+from homeassistant.bootstrap import prepare_setup_platform
 from homeassistant.helpers import (
     generate_entity_id, config_per_platform, extract_entity_ids)
 from homeassistant.components import group, discovery
@@ -45,7 +45,7 @@ def setup(self, config):
         for p_type, p_config in \
                 config_per_platform(config, self.domain, self.logger):
 
-            self._setup_platform(p_type, p_config)
+            self._setup_platform(config, p_type, p_config)
 
         if self.discovery_platforms:
             discovery.listen(self.hass, self.discovery_platforms.keys(),
@@ -115,18 +115,20 @@ def _start_polling(self):
             self._update_entity_states,
             second=range(0, 60, self.scan_interval))
 
-    def _setup_platform(self, platform_type, config, discovery_info=None):
+    def _setup_platform(self, config, platform_type, platform_config,
+                        discovery_info=None):
         """ Tries to setup a platform for this component. """
-        platform_name = '{}.{}'.format(self.domain, platform_type)
-        platform = get_component(platform_name)
+        platform = prepare_setup_platform(
+            self.hass, config, self.domain, platform_type)
 
         if platform is None:
-            self.logger.error('Unable to find platform %s', platform_type)
             return
 
+        platform_name = '{}.{}'.format(self.domain, platform_type)
+
         try:
             platform.setup_platform(
-                self.hass, config, self.add_entities, discovery_info)
+                self.hass, platform_config, self.add_entities, discovery_info)
 
             self.hass.config.components.append(platform_name)