avocado.settings: Introduce docstrings

Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>

avocado/settings.py

@@ -18,15 +18,27 @@ config_path_intree = os.path.join(_config_path_intree, config_filename)
 
 
 class SettingsError(Exception):
+
+    """
+    Base settings error.
+    """
     pass
 
 
 class SettingsValueError(SettingsError):
+
+    """
+    Error thrown when we could not convert successfully a key to a value.
+    """
     pass
 
 
 class ConfigFileNotFound(SettingsError):
 
+    """
+    Error thrown when the main settings file could not be found.
+    """
+
     def __init__(self, path_list):
         super(ConfigFileNotFound, self).__init__()
         self.path_list = path_list
@@ -79,9 +91,18 @@ def convert_value_type(key, section, value, value_type):
 
 class Settings(object):
 
+    """
+    Simple wrapper around ConfigParser, with a key type conversion available.
+    """
+
     no_default = object()
 
     def __init__(self, config_path=None):
+        """
+        Constructor. Tries to find the main settings file and load it.
+
+        :param config_path: Path to a config file. Useful for unittesting.
+        """
         self.config = ConfigParser.ConfigParser()
         self.intree = False
         if config_path is None:
@@ -105,6 +126,17 @@ class Settings(object):
         self.config.read(self.config_path)
 
     def _handle_no_value(self, section, key, default):
+        """
+        What to do if key in section has no value.
+
+        :param section: Config file section.
+        :param key: Config file key, relative to section.
+        :param default: Default value for key, in case it does not exist.
+
+        :returns: Default value, if a default value was provided.
+
+        :raises: SettingsError, in case no default was provided.
+        """
         if default is self.no_default:
             msg = ("Value '%s' not found in section '%s'" %
                    (key, section))
@@ -114,6 +146,21 @@ class Settings(object):
 
     def get_value(self, section, key, key_type=str, default=no_default,
                   allow_blank=False):
+        """
+        Get value from key in a given config file section.
+
+        :param section: Config file section.
+        :param key: Config file key, relative to section.
+        :param key_type: Type of key.
+                It can be either of: str, int, float, bool, list
+        :param default: Default value for the key, if none found.
+        :param allow_blank: Whether an empty value for the key is allowed.
+
+        :returns: value, if one available in the config.
+                default value, if one provided.
+
+        :raises: SettingsError, in case no default was provided.
+        """
         try:
             val = self.config.get(section, key)
         except ConfigParser.Error: