[KLUG Programming] questions on picking data types

[Andrew Thompson]

On Thu, 2004-07-15 at 23:44, Robert G. Brown wrote:
> If any phone number is an instance of a class (aka an object), we can 
> do a really good job of dealing with phone numbers in all kinds of 
> useful ways....
> 
> 1. We seperate the data value from the data representation. We are 
>    thus free to use any data representation we like, and represent
>    it any way (or ways) we want.
> 
> 2. We hide the actual nature of the data value, and protect it
>    from all kinds of erroneous changes.
> 
> 3. We can specify all the code that will work directly with that
>    data, so it will be easier to preserve the integrity of the
>    information, and ensure that the data value does not take on
>    impossible values.
> 
> sounds pretty good, eh? It's what OOP really means, and it's often
> not easyt work. On large, complex systems, it pays off.

Good points, all. Personally, I was ready to jump down people's throats
with "DON'T USE INTEGERS TO STORE SSNs", but it's not really that big a
deal. On the other hand, I still don't consider it wise to assume that a
data element called a number (as in ID number) is best stored that way,
especially if there's any chance its format may change. I mean, you can
talk about accommodating an extra digit, but what if some wiseacre
decided to add a letter instead? And NOT limit it to one of the first
six?

Personally, I would suggest that when it comes to formatted text like
SSNs, internal storage efficiency is somewhat less important than
accurate recognition and representation. Regular expressions all the
way!
-- 
Andrew Thompson <tempes at ameritech.net>
The Imagerie