From: Alistair Grant <akgrant0710@gmail.com>
I think that there's still use for representing a date as a timespan, i.e. a 24 hour period that we can use to find the intersection of times, etc (in addition to adding a timezone offset to a DateTime to figure out the date in a different country). Whether it needs to be a separate class from Timespan I'm not so sure.
From my Smalltalk library: Date methods: asMidnightDateAndTime ^DateAndTime year: self year month: self month day: self dayOfMonth hour: 0 minute: 0 second: 0 pvtSpanFrom: start to: end ^Timespan starting: start asMidnightDateAndTime ending: end asMidnightDateAndTime daySpan ^self pvtSpanFrom: self to: self next monthSpan ^self pvtSpanFrom: self thisMonth to: self nextMonth quarterSpan ^self pvtSpanFrom: self thisQuarter to: self nextQuarter yearSpan ^self pvtSpanFrom: self thisYear to: self nextYear One of the tricky things here is that the result of #daySpan may be 23, 24, or 25 hours, plus or minus a second depending where the leap seconds fall. It is *usually* a 24-hour period, but definitely not always. And of course you can't go *back* from a #daySpan to a Date without reference to a particular time zone (not zone offset, because of course the zone offset can change during a "day").