- use Valuechanged mechanism

components/aheater.py

@@ -1,10 +1,8 @@
 import abc
+from utils.value import AttributeChange
 
 
-class AHeater:
-	def __init__(self):
-		pass
-
+class AHeater(AttributeChange):
 	@abc.abstractmethod
 	def get_power_min(self):
 		pass
@@ -28,7 +26,3 @@ class AHeater:
 	@abc.abstractmethod
 	def getPower(self):
 		return None
-
-	@abc.abstractmethod
-	def connect_power_changed(self, func):
-		pass