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

M.-A. Lemburg mal@lemburg.com
Mon, 04 Mar 2002 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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