From 2231baa060b8a1de5440e702f72a5b29efc9377a Mon Sep 17 00:00:00 2001
From: Ian Rees <ian.rees@gmail.com>
Date: Sun, 19 Feb 2017 13:12:04 +1300
Subject: [PATCH] Throw Python exception if format is unknown.

---
 src/Mod/Mesh/App/AppMeshPy.cpp | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/Mod/Mesh/App/AppMeshPy.cpp b/src/Mod/Mesh/App/AppMeshPy.cpp
index badc123ea..811446389 100644
--- a/src/Mod/Mesh/App/AppMeshPy.cpp
+++ b/src/Mod/Mesh/App/AppMeshPy.cpp
@@ -328,9 +328,14 @@ private:
                           App::Application::Config()["BuildRevisionHash"];
 
             exporter.reset( new AmfExporter(outputFileName, meta, exportAmfCompressed) );
-        } else {
-            // TODO: How do we handle unknown exportFormats?
+
+        } else if (exportFormat != MeshIO::Undefined) {
             exporter.reset( new MergeExporter(outputFileName, exportFormat) );
+
+        } else {
+            std::string exStr("Can't determine mesh format from file name: '");
+            exStr += outputFileName + "'";
+            throw Py::Exception(Base::BaseExceptionFreeCADError, exStr.c_str());
         }
 
         Py::Sequence list(objects);