On Mon, Jul 27, 2015 at 4:13 PM, Steven D'Aprano <st...@pearwood.info> wrote: > To me, Paul's example is a datetime operation: you start with a datetime > (7am today), perform arithmetic on it by adding a period of time (one > day), and get a datetime as the result (7am tomorrow).
Well, OK, let's propose these wordings: It looks like a date operation, ie, add one to the date, but in reality it's a time operation, ie add 86400 seconds to the time. These things sound similar but are very different. I called it a "calendar" operation, because these operation include such things as "add one year", where you expect to get the 27th of July 2016, but you will get the 26th if you use a timedelta, because 2016 is a leap year. So we need to separate date (or calendar) operations from time operations. The same thing goes with months, add 30 days, and you'll sometimes get the same result as if you add one month and sometimes not. timedelta adds time, not days, month or years. Except when you cross a DST border where it suddenly, surprisingly and intentionally may add more or less time than you told it to. //Lennart _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
