[Python-Dev] datetime +/- scalars (int, long, float)?

[M.-A. Lemburg]

Guido van Rossum wrote:
> 
> > Hope you don't mind ;-) ...
> 
> Not at all, we're hoping to arrive at something usable and fun for all!
> 
> > You should name the type timestamp if you want to imply dt + n
> > == dt + n seconds. datetime + n is commonly understood as
> > dt + n *days*.
> 
> Hm, I hadn't thought of that.  To me seconds are the only thing that
> makes sense because that's what a Unix timestamp does, but I haven't
> read or written a lot of commercial code using date/time data.
> 
> Is this just an mxDateTime convention, or is it in wider use?  (URLs
> of docs of other languages / libraries would really help to convince
> me!)

I'm not sure how wide-spread this convention is, but the mxDateTime
users pushed me to it, so there must be some general understanding
in that direction out there ;-)

In mxDateTime I use the following conventions:

	DateTime + n: add n days (each having 86400.0 seconds, so fractions
	              are possible too)

	DateTimeDelta + n: add n seconds

It is of course prevered to write:

	DateTime(...) + DateTimeDelta(...)
	or
	DateTime(...) + RelativeDateTime(...)

since this is more exlicit. There are also a few constants to
make this even easier:

	DateTime(...) + 10 * oneSecond - 20 * oneMinute

-- 
Marc-Andre Lemburg
CEO eGenix.com Software GmbH
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