namer/trace_back: behave on None code_context

diff --git a/migen/fhdl/namer.py b/migen/fhdl/namer.py
index 6a9036628bcf60045649df37b0bf64fdfafcf81f..39d488459fd8e365d75616a797c669aa70564ef1 100644 (file)
--- a/migen/fhdl/namer.py
+++ b/migen/fhdl/namer.py
@@ -16,13 +16,13 @@ def trace_back(name=None):
                        obj = modules[len(modules)-1]
                
                if name is None:
-                       line = inspect.getframeinfo(frame).code_context[0]
-                       m = re.match("[\t ]*([0-9A-Za-z_\.]+)[\t ]*=", line)
-                       if m is None:
-                               name = None
-                       else:
-                               names = m.group(1).split(".")
-                               name = names[len(names)-1]
+                       code_contexts = inspect.getframeinfo(frame).code_context
+                       if code_contexts is not None:
+                               line = code_contexts[0]
+                               m = re.match("[\t ]*([0-9A-Za-z_\.]+)[\t ]*=", line)
+                               if m is not None:
+                                       names = m.group(1).split(".")
+                                       name = names[len(names)-1]
                l.insert(0, (obj, name))
                name = None
                frame = frame.f_back