doc/pc_rpc: add warning about mutable types

sbourdeauducq · sbourdeauducq · commit b93b969e2a63 · 2014-12-04T18:04:54.000+08:00
diff --git a/artiq/management/pc_rpc.py b/artiq/management/pc_rpc.py
@@ -4,6 +4,12 @@
 transparent and uses ``artiq.management.pyon`` internally so that e.g. Numpy
 arrays can be easily used.
 
+Note that the server operates on copies of objects provided by the client,
+and modifications to mutable types are not written back. For example, if the
+client passes a list as a parameter of an RPC method, and that method
+``append()s`` an element to the list, the element is not appended to the
+client's list.
+
 """
 
 import socket
diff --git a/doc/manual/writing_a_driver.rst b/doc/manual/writing_a_driver.rst
@@ -83,6 +83,8 @@ Run it as before, while the controller is running. You should see the message ap
 
 When using the driver in an experiment, for simple cases the ``Client`` instance can be returned by the :class:`artiq.language.core.AutoContext` mechanism and used normally as a device.
 
+:warning: RPC servers operate on copies of objects provided by the client, and modifications to mutable types are not written back. For example, if the client passes a list as a parameter of an RPC method, and that method ``append()s`` an element to the list, the element is not appended to the client's list.
+
 Command-line arguments
 ----------------------
 
