Re: [xml-dev] It is okay for things to break in the future!

["C. M. Sperberg-McQueen" <cmsmcq@blackmesatech.com>]

Michael Kay <mike@saxonica.com> writes:

>> 
>> This is a really, really common mistake made by inexperienced
>> developers - we used to see this all the time in phone number
>> formats, for example. Then mobile numbers came along and changed the
>> formats. And international phone calls became really common,
>> necessitating country codes as a standard part of phone numbers. Etc
>> etc etc :)
>> 
>
> I have had to invent an imaginary US phone number before now in order
> to get past such stupid validation rules.
>
> A golden rule of validation - never force your users to enter
> incorrect data in order to get past your validation rules!

On a more sombre note, consider the tradeoff between the benefits of
having data that's clean according to some rules and the costs of making
data fit those rules.  In 1996, when a bomb threat was called in
regarding a bomb at the Olympic stadium in Atlanta, the 911 operator
spent ten minutes trying to make the 911 system accept the report --
"Centennial Park" was not accepted as the location of interest, because
the system was programmed to require a valid street address with street
name and number.  (I had the same trouble trying to report an apparent
car accident in Baltimore's Druid Hill Park once; the dispatcher could
not enter the report without a street address, so after explaining the
problem I made one up.  In the county where I live, a significant number
of voter registration records have location information like "white
house 3/4 mi southwest of intersection of US 84/285 and NM 399" -- a
data validation routine that expects a house number followed by a street
name is going to be worse than useless.)



-- 
C. M. Sperberg-McQueen
Black Mesa Technologies LLC
http://blackmesatech.com