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

Subject: Re: [boost] [gsoc 2013] draft proposal for chrono::date
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2013-05-04 08:46:58

Le 04/05/13 14:28, Rob Stewart a écrit :
> On May 3, 2013, at 6:24 PM, Anurag Kalia <anurag.kalia_at_[hidden]> wrote:
>> Why are we not using following constructor?
>>
>> date(int year, int month, int day);
> The compiler cannot prevent a user from mistakenly writing date(5, 4, 2013) when the intent was date(2013, 5, 4).
>
>> To clarify my position, benefits are not apparent to me. Since the order is strictly-defined, the writer of code has to remember the ordering in both cases. OTOH an year is typically in thousands:
>>
>> date(2013, 5, 3);
>>
>> It should ring a bell towards the ymd notation. The fact that constructor is named date already gives away its purpose.
> You're presuming familiarity and thoughtful use. Programmers are lazy and frequently hurried, so it's better to prevent errors by forcing date(may, 5, year(2013)).
>
> Your argument WRT the year being larger than any valid day or month is interesting, but applies only if you support years greater than, say, 100.
>
>> I am still waving for functions like:
>>
>> make_ordinal_date(2013, 45);
>> make_week_date(2013, w7, 5);
> Is 5, in the latter, the day of the week? If so, I recommend a constant (or enumeration):
>
> make_week_date(2013, w7, fri);
HH and mine have already these cosntant objects
     extern const weekday sun;
     extern const weekday mon;
     extern const weekday tue;
     extern const weekday wed;
     extern const weekday thu;
     extern const weekday fri;
     extern const weekday sat;
>> Because mixing them with other constructors would be confusing. Keeping the notation to make them seprately, but part of same date class at the end, is
>> something like their relation with actual gregorian calendar.
>>
>> At which point I wonder, why can't we be symmetrical and allow a function like:
>>
>> make_date(2013, 2, 27);
> You could have these, instead, for more consistency:
>
> make_date(2013, 45);
> make_date(2013, w7, fri);
>

The later overload is Ok. The following is ambiguous

make_date(2013, 45);

and need

make_date(year(2013), 45);

BTW, do you prefer w7 or w_7? Or a literal 7_w instead of a constant object?

Vicente