Re: [boost] [gsoc 2013] draft proposal for chrono::date

Subject: Re: [boost] [gsoc 2013] draft proposal for chrono::date
From: Howard Hinnant (howard.hinnant_at_[hidden])
Date: 2013-05-04 12:24:13

On May 4, 2013, at 7:57 AM, Rob Stewart <robertstewart_at_[hidden]> wrote:

>> My still-preferred spelling for the factory functions (yes, more than 1) is:
>> 
>>  date d = year(2013) / month(5) / day(3);
>>  date d = year(2013) / month(5) / 3;
>>  date d = month(5) / day(3) / year(2013);
>>  date d = month(5) / day(3) / 2013;
>>  date d = day(3) / month(5) / year(2013);
>>  date d = day(3) / month(5) / 2013;
> 
> To implement those, you must either introduce intermediate types, like year_and_month, with and overloaded operator /, or you need expression templates to shuffle the argument order before forwarding to a single, checked, date constructor.

Correct, I was strongly leaning towards the former: intermediate types like year_and_month.  And an open question is whether or not year_and_month would be a useful type to the client outside of this role.  E.g. would it be useful to perform month arithmetic on a year_month object?  Would it be helpful to get the number of days in a month out of a year_month object?  Or is year_month simply an implementation detail that the client never sees?

Personally I am still exploring these questions.

Howard