core: better use of C.bool: C.bool only accept basestring subclasses and return the associated constant, C.boolConst return the associated constant for a boolean value

src/core/constants.py

@@ -219,14 +219,12 @@ class Const(object):
 
     @classmethod
     def bool(cls, value):
-        """@return: bool value for any type"""
-        if isinstance(value, str) or isinstance(value, unicode):  # dbus.String is unicode but not str
-            return value.lower() == cls.BOOL_TRUE
-        return bool(value)
+        """@return (bool): bool value for associated constant"""
+        assert isinstance(value, basestring)
+        return value.lower() == cls.BOOL_TRUE
 
     @classmethod
-    def str(cls, value):
-        """@return: str text value for any type"""
-        if isinstance(value, bool):
-            return cls.BOOL_TRUE if value else cls.BOOL_FALSE
-        return str(value)
+    def boolConst(cls, value):
+        """@return (str): constant associated to bool value"""
+        assert isinstance(value, bool)
+        return cls.BOOL_TRUE if value else cls.BOOL_FALSE