Peder Chr. Nørgaard wrote:
Hello Jakub. Thanks for your answer. Well, there is no denying that your double setf makes the problem disappear in my small example. On the other hand, I would not dare to use a solution like this without knowing what the problem really is. And I still don't know that.
Modifying the content of the prototype object of a class - which is what your proposal does - is too likely to have some devastating side effects - now .MD-STATE and .MD-NAME are no longer NIL by default, as specified in the definition of MODEL, they are :PROTOTYPE...
And you are only partially right in that the problem is related to PRINT-OBJECT. I know that the error that I (and you, obviously) get looks like a problem with PRINT-OBJECT - but I think that this is because there is a deeper-lying problem that throws a condition - which then uses PRINT-OBJECT to write out something about the problem - and then that fails, too.
Next step for me will to make an attempt to make PRINT-OBJECT more robust so I can get to the "real" condition.
Good plan.
Note that of course you could just lose the method if that is easier. This is just debugging code and it often bites me, too -- when stuck on a Cells issue I often end up tossing this and other print-objects.
Nothing wrong tho with an effort to make it more robust so it can just stay in place.
kt