[protege-discussion] Metaclass mismatch resulting from drag and drop

[Richard Dunlap]

Build two sibling subclasses of :STANDARD-CLASS, call them :CLASS-1 and 
:CLASS-2.  Build an instance of each metaclass, Class 1-1 and Class 2-1, 
and build a subclass of each of those classes, Class 1-2 and Class 2-2.

Now, drag and drop Class 1-2 as a subclass of Class 2-1 and Class 2-2 as 
a subclass of Class 1-1.  Note that we now have an instance of :CLASS-1 
with a subclass that is an instance of :CLASS-2, and vice versa.  Mayhem 
is likely to ensue; even more mayhem may occur if I drag and drop Class 
2-1 under Class 2-2.  If I do this mischeviously, I deserve what I get; 
but this can also happen when a user inadvertently drags a class on the 
Classes view, and might sensibly happen intentionally while editing the 
class structure in an ontology.

A suggestion: if a drag and drop would result in an inconsistency 
between a child's metaclass and a parent's metaclass, ask the user if 
he/she really wants to do this and, if so, change the child's metaclass 
(and the metaclass of all its children, if it was the root of a tree).