On Thu, 06 Jul 2000 12:56:07 MST, the world broke into rejoicing as
Dylan Paul Thurston <[EMAIL PROTECTED]> said:
> On Thu, Jul 06, 2000 at 12:04:30PM -0500, Jon Trowbridge wrote:
> > For example, certain UK Govt Bonds have decimalized recently. They
> > were previously quoted in 32nds, and are now quoted in 100ths. This
> > is particularly annoying, since you can't convert old prices to new
> > without loss of precision (i.e. 1/32 = 0.03125 = 3/100 + error).
> > ...
>
> I don't know that this is outside the scope of Gnucash, but there are
> more complicated cases that come up frequently: currencies that get
> redefined due to inflation. (Euros are related.) There
> should be a flexible mechanism for dealing with these sorts of
> problems, and I don't know that the shortcut the Bill Gribble's method
> would provide is worth the cost.
>
> Costs of storing denominators with each value include
> - extra storage space
> - additional checks to make sure denominators agree
The problem is that you're _guaranteed_ to have a problem when commodities
get redefined.
Whether it's that there's "old pesos" and "new pesos," or if you move
from "Old Pounds Sterling" to "Decimal Pounds," or Euro transitions,
or stock splits, the situation is the _same_.
You need to be able to distinguish between the "denominations."
For instance, you need to distinguish the pre-split RHAT stock from
post-split RHAT stock.
I will disagree somewhat with Bill's characterization of what I am
looking for; what I'm looking for is not a "data type to represent exact
monetary quantities," but rather a "_set_ of data types to represent
exact quantities of commodities."
As such, you can't separate out the commodity. The value 11/4
doesn't exist; it has to be 11/4 of _something_. I would contend that
the commodity determines the denominator, so that the denominator is
not a property of the _value_, but rather of the _commodity_.
Jon Trowbridge's characterization of (price, Gilts_32) versus (price,
Gilts_100) describes what I rather think we are forcibly _doomed_ to have
to use, and that is independent of what data structure the denominator
sits in. The difference is _not_ merely the terms on which they are
quoted; the securities _are_ different.
Worse still, RHAT stock bought before the split _isn't_ quoted in
different terms. If it trades in integer quantities, then the denominator
for "RHAT_presplit" is the _same_ as the denominator for "RHAT_postsplit."
This has _nothing_ to do with how "monetary values" are represented;
the so-called "RW" and "BG" schemes are _BOTH_ forced to recognize that
the two varieties of RHAT stock _are different_. The "BG" scheme has no
particularly better way to recognize that they are different; since both
are denominated the same, it really doesn't help with this situation,
and still needs "RHAT_presplit" and "RHAT_postsplit" to distinguish
between them.
So I disagree with Jon, in that the "great pain and suffering" is
a _given_, and equally affects _both_ schemes.
By the way, it is _well_ worth taking a look at the GnuE docs;
<http://test.gnue.org/docs/GNUeModuleGuide/x56.html#AEN216>
This page indicates:
"Amounts of money will not be stored as decimal(9,2) because there are
some coutnries (e.g. -in the middle east) where there are 3 digits after
the decimal point. I would suggest to use a signed 64-bit-integer,
unless the database does not support that. In that case, decimal(18,0)
would possibly be appropriate for every currency of the world. In either
case, amounts of money would be expressed in the smallest unit, e.g. in
US-Cents, in British Pence, in German Pfennig and so on.
THere would of course be a currency table in which per currency is
defined how many digits are after the decimal point, and how calculated
amounts in that currency are to be rounded (e.g. - in Switzerland amounts
are rounded by 0.05!)."
[I've fixed a few typos, but don't blame me if the grammar is a bit
painful!]
This is _exactly_ the same issue, and they deal with it in _exactly_
the way that I am suggesting, namely to have amounts stored as integers
representing the smallest unit expressible, and then for there to be a
lookup of what the "generally used" unit is.
In Canada, the US, and the UK, the "smallest unit" is the penny, and
there are 100 of those in the unit typically used (dollars/pounds).
--
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