On Fri, May 29, 2015 at 2:54 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Well, that module has already been rewritten once (which proves that
> there's an audience out there for it). Perhaps somebody will rewrite it
> again to support a non-hardwired set of ranges. Now that we have the
> concept of an extension configuration table, that'd be one possible
> way to fix it ...
I wouldn't bother.
ISBNs already have a UPC-style weighted sum check digit that will
catch the vast majority of errors, including all transposition errors.
You'd have to try hard to fatfinger an ISBN in a way that produced
something that accidentally had a valid check digit.
contrib/isn suffers from a bad case of protecting against Machiavelli
rather than Murphy. The enforcement isn't just obviously wrong, it's
also ridiculous in principle.
You're right, though -- we have better things to worry about.
--
Peter Geoghegan