I would try something like
julia> date("2004-02-29") + year(18)
2022-02-28
But it seems we round the opposite way of your definition.
Ivar
kl. 09:22:00 UTC+2 mandag 21. april 2014 skrev MikeEI følgende:
>
> Jacob, Datetime is great and looking forward to new base.
>
> "Human" time periods are interesting. E.g. important day in Germany is
> 18th birthday (allowed to drive ...). Regulation: You completed 18 years
> (as any other year) on Your birthday 0:00. So the day of one's birth
> counts. If born on a Feb 29, You completed 18 years on Mar 01.
> How would one calculate (18th) birthday <purely> with new base/datetime
> means?
>
>
> Am Montag, 21. April 2014 02:53:18 UTC+2 schrieb Jacob Quinn:
>>
>> Stefan's comment was actually very close to my line of thinking in
>> designing Datetime.jl (which needs to be officially deprecated soon....).
>> After looking through several other libraries/languages of Date
>> implementations, my conclusion is that most end up using an Interval type
>> vs. using Period types because it's too costly to create custom types, or
>> too difficult to overload the needed behaviors to get types talking, or
>> it's just too hard to get good performance.
>> Thankfully, Julia suffers from none of these problems, and so providing a
>> clean Date/Period implementation is clean, simple, and performant. If you
>> have real, full-class Period types, it really simplifies a lot of the
>> interactions and you really don't need an Interval type. TimeTypes
>> represent moments in a timelines at a certain Period precision, and the
>> difference between any two TimeTypes can be returned in the Period type of
>> their precision.
>>
>> -Jacob
>>
>>
>> On Sun, Apr 20, 2014 at 4:55 PM, Stefan Karpinski
>> <[email protected]>wrote:
>>
>>> On Sun, Apr 20, 2014 at 12:05 PM, Harlan Harris <[email protected]>wrote:
>>>
>>>> There are date/time-manipulation libraries where the difference between
>>>> two dates is a date-interval, stored just as the endpoints.
>>>
>>>
>>> This approach has some nice features, but I feel like it's just kicking
>>> the can down the road and not really solving the problem. There's still the
>>> question of what to do about this: date₁ + (date₂ - date₃). In what sense
>>> did you mean to take the interval? Since you're taking the difference and
>>> then adding it to a different starting point, you don't know what about
>>> that difference was relevant. You could require writing something like
>>> this:
>>>
>>> - date₁ + days(date₂ - date₃)
>>> - date₁ + weeks(date₂ - date₃)
>>> - date₁ + months(date₂ - date₃)
>>> - date₁ + years(date₂ - date₃)
>>> - date₁ + workdays(date₂ - date₃)
>>> - date₁ + interestdays(date₂ - date₃)
>>>
>>> etc., although at that point, it's not entirely clear how much going
>>> through an intermediary interval types is really buying you.
>>>
>>
>>
