Merge pull request #758 from ros/update_pr743

Preserve identity of `numpy_msg(T)`

clients/rospy/src/rospy/numpy_msg.py

@@ -74,12 +74,16 @@ def _deserialize_numpy(self, str):
     # pass in numpy module reference to prevent import in auto-generated code
     return self.deserialize_numpy(str, numpy)
 
+_numpy_msg_types = {}
 ## Use this function to generate message instances using numpy array
 ## types for numerical arrays. 
 ## @msg_type Message class: call this functioning on the message type that you pass
 ## into a Publisher or Subscriber call. 
 ## @returns Message class
 def numpy_msg(msg_type):
+    if msg_type in _numpy_msg_types:
+        return _numpy_msg_types[msg_type]
+
     classdict = { '__slots__': msg_type.__slots__, '_slot_types': msg_type._slot_types,
                   '_md5sum': msg_type._md5sum, '_type': msg_type._type,
                   '_has_header': msg_type._has_header, '_full_text': msg_type._full_text,
@@ -90,4 +94,6 @@ def numpy_msg(msg_type):
 
     # create the numpy message type
     msg_type_name = "Numpy_%s"%msg_type._type.replace('/', '__')
-    return type(msg_type_name,(msg_type,),classdict)
+    numpy_type = type(msg_type_name,(msg_type,),classdict)
+    _numpy_msg_types[msg_type] = numpy_type
+    return numpy_type

test/test_rospy/test/unit/test_rospy_numpy.py

@@ -78,3 +78,12 @@ def test_floats(self):
         self.assert_(isinstance(f3.data, numpy.ndarray), type(f3.data))
         v = numpy.equal(f3.data, numpy.array([1.0, 2.1, 3.2, 4.3, 5.4, 6.5], dtype=numpy.float32))
         self.assert_(v.all())
+
+    def test_class_identity(self):
+        from rospy.numpy_msg import numpy_msg
+        self.assert_(isinstance(numpy_msg(Floats)(), numpy_msg(Floats)))
+
+        FloatsNP = numpy_msg(Floats)
+        FloatsNP2 = numpy_msg(Floats)
+
+        self.assert_(FloatsNP is FloatsNP2)