Adding days to std.datetime.Date

[via Digitalmars-d-learn]

On Tuesday, 2 December 2014 at 19:21:35 UTC, Steven Schveighoffer 
wrote:
> On 12/2/14 2:14 PM, Steven Schveighoffer wrote:
>
>> Not an oversight.
>>
>> Date.add and Date.roll are for adding units that are variable.
>>
>> For example, how many days are in a month? Answer: depends on 
>> the month.
>> How many days in a year? Answer: depends on the year.
>>
>> But days are NOT variable, there are exactly 24 hours in a 
>> day. So to
>> add a day, you just add a day with +=.
>
> Aaaand to expand on this, since roll *does* support days, it's 
> because the number being added isn't the important unit, it's 
> the unit above. Hence rolling days means you will stay in the 
> same month.
>
> I'm not exactly sure of the reason behind roll, but I'm sure 
> Jonathan has one :)
>
> -Steve

Oh well, this explanation make so much sense !

Unfortunately, I was not able to find it on the documentation :/

Thank you.