reports and prices [Patch] reworked advanced-portfolio.scm

[Derek Atkins]

Quoting Mike Alexander <mta at umich.edu>:

> --On February 20, 2006 9:15:05 AM -0800 Andrew Sackville-West 
> <andrew at farwestbilliards.com> wrote:
>
>>> One thing I would add to the discussion is to point out that the
>>> pricedb is used for two things in this report (and elsewhere).  It
>>> contains prices in some currency for the commodities (stocks, bonds,
>>> etc.) that are being reported on and it also contains exchange rates
>>> used for converting amounts from one currency to another.  The
>>> report  can infer the first of these from the transactions, but not
>>> the latter.  It really needs the pricedb for that.
>>
>> Yeah, that's definitely a problem. There needs to bhe another
>> exchange-fn, one that doesn't rely on pricedb. And we probably need to
>> create BOTH of them in the report simultaneously because we can't know
>> which "type" of price data we're going to get in advance. 1) for when
>> the pricedb is our source and 2) for when the txn is the source. The
>> question is, how can we get currency exchange data? Can we rely on
>> there being exchange data if someone is working in multiple
>> currencies?
>
> I think you have to rely on that.  I can't think of any other way to 
> get the exchange rates, unless a whole new way of storing them is 
> invented outside the pricedb.  Generally there aren't enough 
> multiple-currency transactions to be useful and they would be hard to 
> find.

Personally, I'm less worried about translating across currencies than I
am about getting a proper stock->currency price.  Let's get the report
working "correctly" for a single currency, and then we can add in support
for multiple currencies.

Granted, I'm not 100% sure how to report multiple currencies, whether to
report it all based on the current exchange rate, or whether to report it
based on the exchange rate closest in time to the actual transactions.

>        Mike

-derek

-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
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