Re: ISN was: Core Extensions relocation

Josh Berkus <josh@agliodbs.com> writes:
> On 11/15/11 7:40 PM, Tom Lane wrote:
>> Peter Geoghegan <peter@2ndquadrant.com> writes:
>>> If we can't put isn out of its misery, a sensible compromise would be
>>> to rip out the prefix enforcement feature so that, for example, ISBN13
>>> behaved exactly the same as EAN13.

>> That might be a reasonable compromise.  Certainly the check-digit
>> calculation is much more useful for validity checking than the prefix
>> checking.

> Sounds good to me.  FWIW, I know that ISBN is being used for some
> library software, so a backwards-compatible fix would be very desirable.

How backwards-compatible do you mean?  Do you think we need to keep the
existing prefix-check logic as an option, or can we just drop it and be
done?

(I'm a bit concerned about the angle that the code has some smarts
currently about where to put hyphens in output.  If we rip that out
it could definitely break application code, whereas dropping a check
shouldn't.)
        regards, tom lane