[kupfer] data: Check that returned Action results are valid

[Ulrik Sverdrup <usverdrup src gnome org>]

commit d1447e3a71148df2606ca690de407abdea9b23c1
Author: Ulrik Sverdrup <ulrik sverdrup gmail com>
Date:   Wed Sep 9 19:32:20 2009 +0200

    data: Check that returned Action results are valid
    
    We use is_valid check

 kupfer/data.py |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)
---
diff --git a/kupfer/data.py b/kupfer/data.py
index 485e747..800c46a 100644
--- a/kupfer/data.py
+++ b/kupfer/data.py
@@ -975,11 +975,14 @@ class DataController (gobject.GObject, pretty.OutputMixin):
 		if sobject:
 			learn.record_search_hit(sobject, self.object_pane.get_latest_key())
 
+		def valid_result(obj):
+			return obj and (not hasattr(obj, "is_valid") or obj.is_valid())
+
 		# handle actions returning "new contexts"
-		if action.is_factory() and ret:
+		if action.is_factory() and valid_result(ret):
 			self.source_pane.push_source(ret)
 			return
-		if action.has_result() and ret:
+		if action.has_result() and valid_result(ret):
 			self.emit("pane-reset", SourcePane, search.wrap_rankable(ret))
 			return
 		elif action.is_async():