[development] code proposal: localization of currency, ...
larry at garfieldtech.com
Sat Oct 20 16:02:34 UTC 2007
On Friday 19 October 2007, Ivan Sergio Borgonovo wrote:
> On Fri, 19 Oct 2007 11:20:27 -0500
> Larry Garfield <larry at garfieldtech.com> wrote:
> > abbreviation, etc.) or mutated from one currency (timezone) to
> > another. The currency mutation rules also change rapidly. Neither
> > format nor mutation is reliably related to language or locality.
> > Sounds like a prime case for a Currency "Value Object" somewhat
> > modeled on the DateTime object (but as a true Value Object, rather
> > than a mutable object). :-)
> Pardon my ignorance, do you have the patience to explain?
> but... you're putting all this responsibility on the site
> administrator that would specify a string to format it.
Correct, because there is no definitive "Pounds Sterling are always always
always displayed in this format" rules. Different clients/use-cases will
want it done differently.
In 2 years, I'm not sure if I've ever had 2 clients ask for their dates to be
displayed in the same format... and they're all in the Midwestern US! :-)
While currency doesn't have as much variation, from earlier on this thread it
certainly looks like there's a fair bit.
In practice, of course, just like there's a DateTime::W3C formatting constant
a fully-featured Currency Value Object would have a Currency::USD formatting
constant that would be used for 80% of all use cases for the US dollar.
> You're not "mutating" one currency in another. You're just expressing
> a currency in the "locale" format.
No, I'm making a distinction between mutating (which involves exchange rates,
which fluctuate hourly) and formatting (which is a string representation of
whatever the current decimal is in some format or another). Yes, mutating is
probably not a task for core. In fact I thing this whole set of
functionality belongs in a Money API module of some sort (there's that TLA
again! <g>). I am primarily drawing parallels between the complexities of
currency and the complexities of time.
> Maybe we should express locale in a more complex way: language +
> "localisation" so that English may be Canadian, UK or US... with some
> system to avoid content duplication
If I'm a stock broker, then my location/timezone is New York, my language is
Spanish (if I'm an immigrant), and I want money displayed in 18 different
currencies using international abbreviations (EUR, USD, etc.) Binding the
format to a locality or language is going to fail at dozens of edge cases.
> Are you referring to exchange rate? That will be an issue of the
> application programmer.
> I'm not interested in an object to store currency... currency will
> appear magically in a variable (task of the app. programmer)
Variable of what type? With what properties? String or double? Who ensures
that it's always restricted to two decimal points, and based on which
rounding scheme (there are several, actually)? There's a lot of logic here
that can/should be encapsulated and generalized. That's exactly what Value
Objects are good for. (I don't mean object on the level of Node or User or
other Assets. I'm talking about more general OO concepts.)
> and they
> have to be formatted accordingly to the locale (maybe a wider concept
> than what locale is now).
My current locale settings have little bearing on the type of money I am
> I'd put date/currency/whatever object out of drupal.
Then you're just guessing about how to format float numbers, which is an
> I think it's not
> the task of a CMS to "understand" content unless you're obliged too.
> So why should you provide a currency object?
... How is it not a CMS's job to understand content? Drupal knows a huge
amount about its content right now.
Larry Garfield AIM: LOLG42
larry at garfieldtech.com ICQ: 6817012
"If nature has made any one thing less susceptible than all others of
exclusive property, it is the action of the thinking power called an idea,
which an individual may exclusively possess as long as he keeps it to
himself; but the moment it is divulged, it forces itself into the possession
of every one, and the receiver cannot dispossess himself of it." -- Thomas
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