// Declares a parameter passed by reference using a CodeDirectionExpression.
CodeDirectionExpression param1 = new CodeDirectionExpression(FieldDirection.Ref, new CodeFieldReferenceExpression( new CodeThisReferenceExpression(), "TestParameter" ));
// Invokes a method on this named TestMethod using the direction expression as a parameter.
CodeMethodInvokeExpression methodInvoke1 = new CodeMethodInvokeExpression(new CodeThisReferenceExpression(), "TestMethod", param1 );

// A C# code generator produces the following source code for the preceeding example code:    

//        this.TestMethod(ref TestParameter);