VectorData : Add method to compare data sources

Author: ericmehl

include/IECorePython/VectorTypedDataBinding.inl

@@ -541,6 +541,11 @@ class VectorTypedDataFunctions
 			);
 		}
 
+		static bool dataSourceEqual( ThisClass &x, ThisClass &y )
+		{
+			return &x.readable() == &y.readable();
+		}
+
 
 	protected:
 		/*
@@ -725,6 +730,7 @@ std::string str<IECore::TypedData<std::vector<TYPE> > >( IECore::TypedData<std::
 			.def("resize", &ThisBinder::resize, "s.resize( size )\nAdjusts the size of s.")	\
 			.def("resize", &ThisBinder::resizeWithValue, "s.resize( size, value )\nAdjusts the size of s, inserting elements of value as necessary.")	\
 			.def("hasBase", &ThisClass::hasBase ).staticmethod( "hasBase" ) \
+			.def("_dataSourceEqual", &ThisBinder::dataSourceEqual, "Returns true if the given object points to the same source data as this object.")	\
 			.def("__str__", &str<ThisClass> )	\
 			.def("__repr__", &repr<ThisClass> )	\
 

test/IECore/VectorData.py

@@ -1341,6 +1341,31 @@ def test( self ) :
 
 		self.assertEqual( d2, d )
 
+class TestSourceDataEquality( unittest.TestCase ) :
+
+	def test( self ) :
+
+		a = IECore.FloatVectorData( [ 1, 2, 3 ] )
+		b = IECore.FloatVectorData( [ 4, 5, 6 ] )
+
+		self.assertTrue( a._dataSourceEqual( a ) )
+		self.assertFalse( a._dataSourceEqual( b ) )
+
+		ca = a.copy()
+		self.assertTrue( a._dataSourceEqual( ca ) )
+
+		ca[0] = 42
+		self.assertFalse( a._dataSourceEqual( ca ) )
+
+		ca2 = a.copy()
+		ca3 = ca2.copy()
+		self.assertTrue( a._dataSourceEqual( ca2 ) )
+		self.assertTrue( a._dataSourceEqual( ca3 ) )
+		
+		a[0] = 99
+		self.assertFalse( a._dataSourceEqual( ca2 ) )
+		self.assertTrue(ca2._dataSourceEqual( ca3 ) )
+
 if __name__ == "__main__":
     unittest.main()