On Mon, 4 Mar 2002, Kevin Jacobs wrote:
The concept of a "day" can be somewhat ambiguous. I've seen datetime implementations that will apply DST changes when asked to adjust by days, but not when asked to adjust by seconds, hours or minutes. So, in the general case of a DST aware datetime object,
t + Delta(days=1) != t + Delta(hours=24)
even when ignoring leap-seconds and other micro-adjustments. So lets define adjustments by "days" for the base datetime object in terms of 86400.0 seconds. A DST aware datetime subclass can then be made that does the more complex day-based arithmetic.
Or, someone implementing datetime as (julian: integer, seconds: float) might prefer to let adjustment by "days" be in terms of 1 day. A DST aware datetime subclass can then be made that does the more complex time-based arithmetic.