From: Francis Hwang <sera@...>
Date: 2004-10-30T22:46:59+09:00
Subject: Re: Money Class (was Re: Rounding error, (100.0 * 9.95).to_i == 994)


On Oct 30, 2004, at 9:05 AM, Brian Schr�der wrote:

> Why not just use integer valued cent-counts?

Sometimes that's not sufficient. If you're an organization that has to 
deal with quantities and amounts priced in multiple currencies, you 
have to store both the number and the currency itself. 5 Euros, 10 
dollars, 42000 Korean won, etc. Then if you are adding or comparing 
them to one another you have to figure out how to sensibly model that. 
What's 5 Euros plus 10 dollars? Does it matter that the answer to that 
question changes over time, as exchange rates are constantly 
fluctuating?

It's a pretty interesting little domain. Martin Fowler devotes a few 
pages to it in Analysis Patterns.

F.