Re: [SMW-devel] implementing Type:Currency

[Tony B. <ton...@ka...>]

On Fri, Aug 04, 2006 at 10:56:11PM -0700, S Page wrote:
> (Back in May Tony Bowden and MovGP0 talked about currency conversion.)
> FYI, using the data-driven linear conversion code checked into CVS, I 
> was able to build currency conversion.

Nice approach.

> The time-dependent nature of currency conversion has some tricky 
> problems.  If pages prominently displayed "Currency values converted as 
> of  $lastmod" (normally this is shown in the page footer). that would 
> hint at the accuracy of the tooltips and factbox.  

I think there's two different types of conversion needed. There's the
'current value' that will vary over time in other currencies, and the
'historic price' that shouldn't. For example, if you store a list of
things purchased on your credit card, then a payment you made may
have been for CA$100, but you don't want the US$ version changing over
time - you want it fixed at whatever the exchange rate was at the time.

As I think I've noted before, my needs are generally for the second of
these, so I'm less interested in the automatic conversion than other
people. I'm happy to specify both the foreign price and local price
explicitly and don't want anything changing those later!

> Another issue is supporting currency prefixes like $59.95 and ?20.  It's 
> easier to support this in entered Wiki text than on display which 
> assumes number followed by unit is the correct float format.  

This is more of an issue for me. Having the currency string come after
the amount just looks weird. (Except of course for those currencies
where it is supposed to!)

> be a compelling reason to implement format strings, or to build a 
> dedicated currency datatype that still reads conversion factors from its 
> Type page.

I'm not sure what exactly is meant by "format strings" but it sound like
that's going to be a good idea! :)

Thanks for the work on this,

Tony