[Apologies if this is a dumb question...]
AFAICT there's no way for me to try to ACCEPT a pathname that is constrained to refer to a file that already exists. Is this true?
I could imagine trying to create a new presentation subtype of pathname that would meet this constraint.
But doesn't it seem that it would have been reasonable to make a pathname a compound type that would allow for constraints?
Also, I have been looking at the Allegro CLIM UG and the CLIM 2 spec, and I have not been able to determine what sort of guarantees ACCEPT provides. When it reads one of my previously-existing pathnames, for example, will it be obligated to run presentation-typep at some point to check that the filename is actually previously-extant? Or is it allowed to just hope that the user has typed in a string that refers to a previously-existing filename, instead of the name of his grandmother's dog?
I don't know exactly how to test this, but my rudimentary tests with trace seem to indicate that ACCEPT isn't doing any verification. Is that right?
If so, and I want to enforce this constraint, should I be making an :around method for accept that will check the constraint and either return if it's satisfied, or invoke call-next-method if it's violated?
I would have thought that there would have been some protocol for bad input (e.g., raise a particular exceptionq), but my cursory examination of the spec doesn't reveal any such.
Thanks, Robert