From: Hugh Sasse Staff Elec Eng <hgs@...>
Date: 2003-08-22T06:45:45+09:00
Subject: Re: Class variables - a surprising result

On Fri, 22 Aug 2003, Kurt M. Dresner wrote:

> > I have run into this because I'm working on a loans
> > system, and each item needs a unique id, which I've allocated as an
> > error correcting code.  This gives me 46000 items. But if I have to
> > use the same class variable to number my users uniquely as well as
> > the items they borrow, that uses up space in my limited range.
>
> Um, this screams "instance variables" to me...

Each has an instance var holding its number. Somewhere I must keep
the next available number, in such a way that the new item gets a
different one.

Now I've put it in those terms I might be better having a factory
class which has an instance var for the number, and calls the
constructor for the object I want numbered with that fresh
number....

    ... Item.new(@next_free) ...

Why didn't I think of that before? Keep the number somewhere else
than the class I want to count.
>
> What does your class represent, a user or a loan?

I have users, loans, and items to be loaned. The loans aren't
numberd, just the users and items.
>
> -Kurt
>
>
        Hugh