Improve flexibility of the loader
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0c7b6e26aa
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1 changed files with 47 additions and 17 deletions
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@ -3,7 +3,17 @@ homeassistant.loader
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~~~~~~~~~~~~~~~~~~~~
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Provides methods for loading Home Assistant components.
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This module has quite some complex parts. I have tried to add as much
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documentation as possible to keep it understandable.
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Components are loaded by calling get_component('switch') from your code.
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If you want to retrieve a platform that is part of a component, you should
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call get_component('switch.your_platform'). In both cases the config directory
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is checked to see if it contains a user provided version. If not available it
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will check the built-in components and platforms.
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"""
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import os
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import sys
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import pkgutil
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import importlib
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@ -30,22 +40,27 @@ def prepare(hass):
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pkgutil.iter_modules(components.__path__, 'homeassistant.components.'))
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# Look for available custom components
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custom_path = hass.get_config_path("custom_components")
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# Ensure we can load custom components from the config dir
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sys.path.append(hass.config_dir)
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if os.path.isdir(custom_path):
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# Ensure we can load custom components using Pythons import
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sys.path.insert(0, hass.config_dir)
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try:
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# pylint: disable=import-error
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import custom_components
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# We cannot use the same approach as for built-in components because
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# custom components might only contain a platform for a component.
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# ie custom_components/switch/some_platform.py. Using pkgutil would
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# not give us the switch component (and neither should it).
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AVAILABLE_COMPONENTS.extend(
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item[1] for item in
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pkgutil.iter_modules(
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custom_components.__path__, 'custom_components.'))
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# Assumption: the custom_components dir only contains directories or
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# python components. If this assumption is not true, HA won't break,
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# just might output more errors.
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for fil in os.listdir(custom_path):
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if os.path.isdir(os.path.join(custom_path, fil)):
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AVAILABLE_COMPONENTS.append('custom_components.{}'.format(fil))
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except ImportError:
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# No folder custom_components exist in the config directory
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pass
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else:
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AVAILABLE_COMPONENTS.append(
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'custom_components.{}'.format(fil[0:-3]))
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def get_component(comp_name):
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@ -61,8 +76,10 @@ def get_component(comp_name):
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# an exception because it will try to import the parent.
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# Because of this behavior, we will approach loading sub components
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# with caution: only load it if we can verify that the parent exists.
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# We do not want to silent the ImportErrors as they provide valuable
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# information to track down when debugging Home Assistant.
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# First check config dir, then built-in
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# First check custom, then built-in
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potential_paths = ['custom_components.{}'.format(comp_name),
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'homeassistant.components.{}'.format(comp_name)]
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@ -76,17 +93,30 @@ def get_component(comp_name):
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continue
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try:
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_COMPONENT_CACHE[comp_name] = importlib.import_module(path)
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module = importlib.import_module(path)
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# In Python 3 you can import files from directories that do not
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# contain the file __init__.py. A directory is a valid module if
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# it contains a file with the .py extension. In this case Python
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# will succeed in importing the directory as a module and call it
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# a namespace. We do not care about namespaces.
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# This prevents that when only
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# custom_components/switch/some_platform.py exists,
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# the import custom_components.switch would succeeed.
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if module.__spec__.origin == 'namespace':
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continue
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_LOGGER.info("Loaded %s from %s", comp_name, path)
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return _COMPONENT_CACHE[comp_name]
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_COMPONENT_CACHE[comp_name] = module
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return module
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except ImportError:
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_LOGGER.exception(
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("Error loading %s. Make sure all "
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"dependencies are installed"), path)
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# We did find components but were unable to load them
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_LOGGER.error("Unable to load component %s", comp_name)
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_LOGGER.error("Unable to find component %s", comp_name)
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return None
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