config: add ConfigurableObject object class

mylib/config.py

@@ -948,3 +948,87 @@ class Config:  # pylint: disable=too-many-instance-attributes
             ("%s.ini" % self.shortname) if self.shortname
             else "config.ini"
         )
+
+
+class ConfigurableObject:
+    """
+    Base class of configurable object
+
+    This class provide a way to configure an object using :
+      - mylib.config.Config object
+      - argparse.Namespace object
+      - kwargs passed to __init__ method
+    """
+
+    # Configuration object name (used for default options prefix and config section)
+    # Note: required if options_prefix or/and config_section parameters not provided
+    # to __init__ method.
+    _config_name = None
+
+    # Configuration comment (used for config section)
+    _config_comment = None
+
+    # Default options value
+    # Important: all supported options MUST HAVE a default value defined
+    _defaults = {}
+
+    # Store options passed throuht __init__ method
+    _kwargs = {}
+    _options = {}
+    _options_prefix = None
+    _config = None
+    _config_section = None
+
+    def __init__(self, options=None, options_prefix=None, config=None, config_section=None,
+                 **kwargs):
+
+        for key, value in kwargs.items():
+            assert key in self._defaults, "Unknown %s option" % key
+            self._kwargs[key] = value
+
+        if options:
+            self._options = options
+            if options_prefix is not None:
+                self._options_prefix = options_prefix
+            elif self._config_name:
+                self._options_prefix = self._config_name + '_'
+            else:
+                raise Exception('No configuration name defined for %s' % __name__)
+
+        if config:
+            self._config = config
+            if config_section:
+                self._config_section = config_section
+            elif self._config_name:
+                self._config_section = self._config_name
+            else:
+                raise Exception('No configuration name defined for %s' % __name__)
+
+    def _get_option(self, option, default=None, required=False):
+        """ Retreive option value """
+        if self._kwargs and option in self._kwargs:
+            return self._kwargs[option]
+
+        if self._options and hasattr(self._options, self._options_prefix + option):
+            return getattr(self._options, self._options_prefix + option)
+
+        if self._config and self._config.defined(self._config_section, option):
+            return self._config.get(self._config_section, option)
+
+        assert not required, "Options %s not defined" % option
+
+        return default if default is not None else self._defaults.get(option)
+
+    def configure(self, comment=None, ** kwargs):
+        """ Configure options on registered mylib.Config object """
+        assert self._config, "mylib.Config object not registered. Must be passed to __init__ as config keyword argument."
+
+        return self._config.add_section(
+            self._config_section,
+            comment=comment if comment else self._config_comment,
+            loaded_callback=self.initialize, **kwargs)
+
+    def initialize(self, loaded_config=None):
+        """ Configuration initialized hook """
+        if loaded_config:
+            self.config = loaded_config  # pylint: disable=attribute-defined-outside-init