From 6aaf6c87894eac10c07150125682db7025918789 Mon Sep 17 00:00:00 2001
From: Sebastien Bourdeauducq <sb@m-labs.hk>
Date: Fri, 9 Sep 2016 09:06:59 +0800
Subject: [PATCH] language/environment: only call prepare automatically if it
 exists

---
 artiq/language/environment.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/artiq/language/environment.py b/artiq/language/environment.py
index 3a3bed0e4..2fd2b39b1 100644
--- a/artiq/language/environment.py
+++ b/artiq/language/environment.py
@@ -380,9 +380,10 @@ class EnvExperiment(Experiment, HasEnvironment):
     Most experiment should derive from this class."""
     def prepare(self):
         """The default prepare method calls prepare for all children, in the
-        order of instantiation."""
+        order of instantiation, if the child has a prepare method."""
         for child in self.children:
-            child.prepare()
+            if hasattr(child, "prepare"):
+                child.prepare()
 
 
 def is_experiment(o):