I don't see any substantive difference beteween using strings and
using numbers to identify the basis. My main reason for suggesting
string representation was so that when I look at an odf formula, I can
use the string as a neumonic instead of having to go back to the
standard to find out what basis==0 means.
wt
On Fri, Apr 18, 2008 at 12:59 PM, <> wrote:
>
> From a storage perspective, is there any backwards compatibility problem
> caused by moving from our current integer bases to strings, where five of
> the strings are "0", "1", "2", "3" and "4" ?
>
> If we did that we could add others like "NYSE_X25", "ISDA_Rule25" or
> whatever.
>
> -Rob
>
>
> "David A. Wheeler" <> wrote on 04/18/2008 02:56:31 PM:
>
>
>
> > In general, the formula specification tries to follow EXISTING
> > conventions wherever reasonable. _All_ spreadsheet implementations
> > use integer "basis" values for all their functions that have
> > such a parameter. I agree that using a string has its merits,
> > but using an integer is reasonable enough.
> > In fact, integers make it easy to create "ranges", and would
> > actually _ease_ transitions if there are differing interpretations
> > of basis values.
> >
> > I think we should try to AVOID spec'ing something incompatible
> > with all existing implementations unless we have a pressing
> > need to do so, and I don't think this is compelling. That said...
> >
> >
> > > On Fri, Apr 18, 2008 at 7:00 AM, David A. Wheeler
> > <> wrote:
> > > > The problem is that basis values need not be a constant in the
> > cell; it might be
> > > > from another cell and/or a calculation (directly or indirectly),
> e.g.:
> > > > YEARFRAC([.A5];[.B5];[.C5]+1)
> >
> > Warren Turkal:
> > > This seems like an unrealistic use case. In all sincerity, why would
> > > someone do that? Is it common? I just don't see folks selecting the
> > > basis by saying I want whatever the basis is identified by taking the
> > > identifier of some basis (e.g. actual/actual) and adding 1 to it.
> >
> > You're right, that was a silly example.
> >
> > But a more realistic one is:
> >
> > YEARFRAC([.A5];[.B5]; IF(CONVENTION="US"; 0; 4))
> >
> > Now the filter has to start digging through the expression tree,
> > or end up with a complicated resulting expression. Ugh.
> >
> > > Having said that. If people do it, import filters can just map it to
> > > whatever fixed string it's value corresponds to on import...
> >
> > Yes, import filters can fix it... but let's try to make it easy on
> > the filters!
> > Simple implementation is very important for getting a spec implemented.
> >
> > Switching from an integer to a string representation does NOT
> > really ease the "different basis interpretation" problem at all.
> > It just means that EVERYONE has to convert, instead of only
> > SOME people having to convert. That makes things worse, not better.
> > Integers also tend to be more efficient, and make it easy to
> > do conversions of whole groups (e.g., we could make the
> > Excel 2007 and OOXML conventions differ by 128, and then
> > adding/subtracting 128).
> >
> > Since everyone uses integers NOW for basis values, let's try to stick
> > with that if it's practical to do so. And I think it is.
> >
> > --- David A. Wheeler
> >
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