When an application invokes a generic function, and no methods at all have been defined for that generic function, GOOPS calls the
no-methodgeneric function. The default method callsgoops-errorwith an appropriate message.
When an application applies a generic function to a set of arguments, and no methods have been defined for those argument types, GOOPS calls the
no-applicable-methodgeneric function. The default method callsgoops-errorwith an appropriate message.
When a generic function method calls
(next-method)to invoke the next less specialized method for that generic function, and no less specialized methods have been defined for the current generic function arguments, GOOPS calls theno-next-methodgeneric function. The default method callsgoops-errorwith an appropriate message.