Add __hash__ functions where necessary

According to [1], A class that overrides __eq__() and does not define
__hash__() will have its __hash__() implicitly set to None. When the
__hash__() method of a class is None, instances of the class will raise
an appropriate TypeError when a program attempts to retrieve their hash
value, and will also be correctly identified as unhashable when checking
isinstance(obj, collections.Hashable).

A few other classes also implement __eq__ but we don't seem to use them
anywhere as keys in dictionaries, so they don't need to implement the
__hash__ function yet.

[1] https://docs.python.org/3.4/reference/datamodel.html?highlight=hash#object.__hash__

partial blueprint heat-python34-support

Change-Id: Idf24d462f386927496950e65a24e41b9aef69281

heat/engine/function.py

@@ -125,6 +125,9 @@ class Function(object):
             return NotImplemented
         return not eq
 
+    def __hash__(self):
+        return id(self)
+
 
 def resolve(snippet):
     while isinstance(snippet, Function):

heat/engine/resource.py

@@ -296,6 +296,9 @@ class Resource(object):
             return result
         return not result
 
+    def __hash__(self):
+        return id(self)
+
     def metadata_get(self, refresh=False):
         if refresh:
             self._rsrc_metadata = None

heat/engine/rsrc_defn.py

@@ -395,6 +395,13 @@ class ResourceDefinition(ResourceDefinitionCore, collections.Mapping):
 
         raise KeyError(key)
 
+    def __hash__(self):
+        """
+        Return a hash of the ResourceDefinition object.
+        """
+        warnings.warn(self._deprecation_msg, DeprecationWarning)
+        return super(ResourceDefinition, self).__hash__()
+
     def __len__(self):
         """
         Return the number of available CFN template keys.

heat/tests/utils.py

@@ -126,6 +126,9 @@ class PhysName(object):
         # ignore the stack portion of the name, as it may have been truncated
         return res == self.res
 
+    def __hash__(self):
+        return id(self)
+
     def __ne__(self, physical_name):
         return not self.__eq__(physical_name)