Only check this if we're in Python 2, otherwise types.InstanceType does not exist

Author: gonzalocasas

src/compas_fab/backends/ros/service_description.py

@@ -10,6 +10,7 @@
 
 import types
 
+import compas
 from roslibpy import Service
 from roslibpy import ServiceRequest
 
@@ -32,13 +33,14 @@ def __init__(self, name, service_type, request_class=None, response_class=None,
 
     def call(self, client, request, callback, errback):
         def inner_handler(response_msg):
-            # IronPython sometimes decides it's a good idea to use an old-style class
-            # to pass the response_msg around, so we need to make sure we turn it into
-            # a proper ServiceResponse again
-            # https://github.com/compas-dev/compas_fab/issues/235
-            is_old_style_class = isinstance(response_msg, types.InstanceType)
-            if is_old_style_class:
-                response_msg = dict(response_msg)
+            if not compas.PY3:
+                # IronPython sometimes decides it's a good idea to use an old-style class
+                # to pass the response_msg around, so we need to make sure we turn it into
+                # a proper ServiceResponse again
+                # https://github.com/compas-dev/compas_fab/issues/235
+                is_old_style_class = isinstance(response_msg, types.InstanceType)
+                if is_old_style_class:
+                    response_msg = dict(response_msg)
             response_object = self.response_class.from_msg(response_msg)
 
             # Validate the response if there's a validator function assigned