[Python-Dev] Fixed Decimal types

[Andy Robinson]

> >> However, unlike RPG, we should probably ensure 
> >> that attempts to overflow or underflow the scale 
> >> result in NaN or Overflow conditions, rather
> >> than assuming the user is right and losing 
> >> the significant digits.
>  
> > Since this would be based on infinite-precision
> numbers, I don't
> > think that this would be an issue.


Three very general observations before I disappear for
Christmas:

(1) I think there is great mileage in combining the
fixed-decimal concept with Martin Fowler's Quantity
pattern, so that a variable could be defined as not
just two decimal places but also (say) "GBP" or "USD",
and it would be an error to add the two.  Same applies
for adding metres, kilograms and other quantities. 
There has also been discussion that the 'type' of a
quantity should determine what math should apply.

(2) If Python is going to be used increasingly in
eCommerce, it should be good at dealing with money -
maybe not in the core language, but we should aim for
one standard package.  

(3) We have a python-finance list
(python-finance@egroups.com), recently generalized to
cover business systems, which is a good place to
discuss this if anyone wants to.  There are people
there who have time, would love to prototype something
(indeed some work started in this area 3 months back),
and would use it at work too.  This would be an ideal
first target for that group - or indeed for a
finance-sig.  I'll pursue this in the New Year.

Merry Christmas,

Andy

=====
Andy Robinson
Robinson Analytics Ltd.
------------------
My opinions are the official policy of Robinson Analytics Ltd.
They just vary from day to day.

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