Add specific repr implementation for enums

trans/transpiler/phases/emit_cpp/class_.py

@@ -25,6 +25,13 @@ class ClassVisitor(NodeVisitor):
         yield "py_type(const py_type&) = delete;"
         yield "py_type(py_type&&) = delete;"
 
+        if getattr(node.type, "is_enum", False):
+            yield "int value;"
+            yield "operator int() const { return value; }"
+            yield "void py_repr(std::ostream &s) const {"
+            yield f's << "{node.name}." << value;'
+            yield "}"
+        else:
             yield "void py_repr(std::ostream &s) const {"
             yield "s << '{';"
             for i, (name, memb) in enumerate(node.type.members.items()):