avoid loops

diff --git a/grc/python/Port.py b/grc/python/Port.py
index 2f7af855c53ecbb85243d70121a872fd735210ef..80d9fcaae1f2bdbf8afb5b665a788685cb33cbcf 100644 (file)
--- a/grc/python/Port.py
+++ b/grc/python/Port.py
@@ -21,12 +21,21 @@ from .. base.Port import Port as _Port
 import Constants
 
 def _get_source_from_virtual_sink_port(vsp):
+       """
+       Resolve the source port that is connected to the given virtual sink port.
+       Use the get source from virtual source to recursively resolve subsequent ports. 
+       """
        try: return _get_source_from_virtual_source_port(
                vsp.get_enabled_connections()[0].get_source())
-       except: raise Exception, 'Could not resolve source for virtual sink port', vsp
+       except: raise Exception, 'Could not resolve source for virtual sink port %s'%vsp
 
-def _get_source_from_virtual_source_port(vsp):
+def _get_source_from_virtual_source_port(vsp, traversed=[]):
+       """
+       Recursively resolve source ports over the virtual connections.
+       Keep track of traversed sources to avoid recursive loops.
+       """
        if not vsp.is_virtual_source(): return vsp
+       if vsp in traversed: raise Exception, 'Loop found when resolving virtual source %s'%vsp
        try: return _get_source_from_virtual_source_port(
                _get_source_from_virtual_sink_port(
                        filter(
@@ -36,9 +45,9 @@ def _get_source_from_virtual_source_port(vsp):
                                        vsp.get_parent().get_parent().get_enabled_blocks(),
                                ),
                        )[0].get_sink(vsp.get_key())
-               )
+               ), traversed + [vsp],
        )
-       except: raise Exception, 'Could not resolve source for virtual source port', vsp
+       except: raise Exception, 'Could not resolve source for virtual source port %s'%vsp
 
 class Port(_Port):