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

2002年3月04日 14:50:43 +0100

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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