Hi Abdelghani, PPCompositeParser use reflection to initialize all the parsers stored in instance variables. Your problem comes from the fact that your "model" instance variable is not intended to stores a parser as other instance variables do. To exclude your iv from PPCompositeParser machinery you can redefine #ignoredNames on class-side: PPMyLanguageGenerator class>>ignoredNames ^ super ignoredNames, #(model) But it looks like #model is supposed to be the result of your generator? If this is the case I think that you should not store it in an instance variable. Parsers are supposed to be stateless. Instead each production rule should return a part of your model (using ==> [ … ]) that you then compose progressively in other rules. Terminal rules return the leaves of your model and non-terminal rules compose the results. The start production rule then returns the full model. Look at the other subclasses of PPCompositeParser for insight. HTH, Camille