USD DataAlgo : Fix handling of types not known to dispatch()

We now return a sentinel instead of throwing an exception. This is consistent with our existing handling of types known to `dispatch()` but without a corresponding USD type.

Author: johnhaddon

Changes

@@ -11,6 +11,7 @@ Fixes
 
 - ShaderNetworkAlgo : Fixed crash caused by cyclic connections in `removeUnusedShaders()`.
 - ShaderStateComponent : Fixed GL rendering failures caused by unsupported values for texture parameters.
+- IECoreUSD::DataAlgo : Fixed exceptions thrown by `toUSD()` and `valueTypeName()` when passed datatypes not supported by `dispatch()`. An empty VtValue or SdfValueTypeName is now returned instead.
 
 Build
 -----

contrib/IECoreUSD/src/IECoreUSD/DataAlgo.cpp

@@ -400,7 +400,15 @@ struct VtValueFromData
 
 pxr::VtValue IECoreUSD::DataAlgo::toUSD( const IECore::Data *data, bool arrayRequired )
 {
-	return IECore::dispatch( data, VtValueFromData(), arrayRequired );
+	try
+	{
+		return IECore::dispatch( data, VtValueFromData(), arrayRequired );
+	}
+	catch( const IECore::Exception & )
+	{
+		// Type not supported by `dispatch()`.
+		return VtValue();
+	}
 }
 
 pxr::TfToken IECoreUSD::DataAlgo::role( GeometricData::Interpretation interpretation )
@@ -503,5 +511,13 @@ struct VtValueTypeNameFromData
 
 pxr::SdfValueTypeName IECoreUSD::DataAlgo::valueTypeName( const IECore::Data *data )
 {
-	return IECore::dispatch( data, VtValueTypeNameFromData() );
+	try
+	{
+		return IECore::dispatch( data, VtValueTypeNameFromData() );
+	}
+	catch( const IECore::Exception & )
+	{
+		// Type not supported by `dispatch()`.
+		return SdfValueTypeName();
+	}
 }

contrib/IECoreUSD/test/IECoreUSD/DataAlgoTest.py

@@ -35,6 +35,8 @@
 import unittest
 import imath
 
+import pxr.Sdf
+
 import IECore
 import IECoreUSD
 
@@ -68,6 +70,9 @@ def testValueTypeNameBinding( self ) :
 
 		self.assertEqual( IECoreUSD.DataAlgo.valueTypeName( IECore.Color3fData( imath.Color3f( 0.0 ) ) ).type.typeName, "GfVec3f" )
 
+		self.assertEqual( IECoreUSD.DataAlgo.valueTypeName( IECore.PathMatcherData() ), pxr.Sdf.ValueTypeName() )
+		self.assertEqual( IECoreUSD.DataAlgo.valueTypeName( IECore.CompoundData() ), pxr.Sdf.ValueTypeName() )
+
 	def testToUSDBinding( self ) :
 
 		# Note : On the C++ side we are converting to VtValue, but the
@@ -77,6 +82,8 @@ def testToUSDBinding( self ) :
 			( IECore.IntData( 10 ), 10 ),
 			( IECore.FloatData( 2.5 ), 2.5 ),
 			( IECore.IntVectorData( [ 1, 2, 3 ] ), [ 1, 2, 3 ] ),
+			( IECore.PathMatcherData(), None ),
+			( IECore.CompoundData(), None ),
 		] :
 			self.assertEqual( IECoreUSD.DataAlgo.toUSD( data ), value )