Re: [boost] Date-Time

From: Rob Stewart (stewart_at_[hidden])
Date: 2004-04-13 17:25:52

From: Val Samko <boost_at_[hidden]>
> Tuesday, April 13, 2004, 4:46:11 PM, you wrote:
> 
> RS> I didn't say just add 30 days.  I said I'd expect it to be the
> RS> same day of the month in the following month and if there is no
> RS> such day in that month, then I'd expect it to be 30 days ahead.
> 
> Do you actually need such a functionality in any applications?

No.  The point I was making is that were I to call such a
function, that's the behavior I'd expect.  Does not having a
current need for it make it less valid?

> RS> Now, one might argue that adding a month should just be adding 30
> RS> days then, but that is already possible.  I see add_month() as
> RS> the means to get closer to the human notion of getting the same
> RS> day of the next month, with a clear, mathematical fallback.
> falling back to the last day of the month is a perfect "mathematical"
> fallback as well. It's just a matter of documentation.

It isn't mathematical, by which I meant predictable, without
accounting for whether the day of the current month is available
in the subsequent month.  That is, yours may fall back anywhere
from zero to three days.  Mine is certain to advance to the same
day of the month or exactly 30 days beyond the start; that's far
more predictable.

> >> Anyway, what other variations do you propose, which can not be
> >> achieved by just adding N days?
> 
> RS> I don't know what other variations may arise.  We've already seen
> RS> two, so distinct but clear names already seem warranted.
> 
> I understand this if you actually need the functionality you described
> in any applications. Otherwise, I'd hate to type
> add_month_or_fallback_to_last_day each time I need this simple
> operation.

I don't think it must be that dramatic.  If the function is to
have a unique name, rather than using one of the other techniques
I mentioned, I should think that "add_month_with_fallback"
would be sufficient to clarify its behavior.

It boils down to this: does everyone but me think the fallback
behavior is "correct?"  If so, ignore me.  I can always implement
my own "add_month." If not, then yours should not be *the*
definition of "add_month" should it?  In that case, shouldn't you
mitigate the potential for confusion and allow for different
schemes?

-- 
Rob Stewart                           stewart_at_[hidden]
Software Engineer                     http://www.sig.com
Susquehanna International Group, LLP  using std::disclaimer;