engine: handle new attribute annotation `is_optional`

[nit.git] / src / interpreter / naive_interpreter.nit

diff --git a/src/interpreter/naive_interpreter.nit b/src/interpreter/naive_interpreter.nit
index bbe07d1..23d3ba1 100644 (file)
--- a/src/interpreter/naive_interpreter.nit
+++ b/src/interpreter/naive_interpreter.nit
@@ -1497,7 +1497,12 @@ redef class AAttrPropdef
                        return evaluate_expr(v, recv, f)
                else if mpropdef == mwritepropdef then
                        assert args.length == 2
-                       v.write_attribute(attr, recv, args[1])
+                       var arg = args[1]
+                       if is_optional and arg.mtype isa MNullType then
+                               var f = v.new_frame(self, mpropdef, args)
+                               arg = evaluate_expr(v, recv, f)
+                       end
+                       v.write_attribute(attr, recv, arg)
                        return null
                else
                        abort