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    constexpr auto ymd {year(2021)/January/day(23)}; (std::chrono::operator/) c++ en.cppreference.com
    raymii avatar via raymii 5 months ago |
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    | 11 comments
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      raymii avatar raymii 5 months ago | link

      A prime example of nice c++. Operator/ is also used as a path separator in std::filesystem: https://en.cppreference.com/w/cpp/filesystem/path/operator_slash

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        syn-ack avatar syn-ack 5 months ago | link

        I disagree. Language features that hide control flow and make things non-obvious such as changing the meaning of the division operator lean towards abuse over use, in my opinion. It’s not like the result looks particularly good from a syntactic perspective, either (imo).

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          icefox avatar icefox 5 months ago | link

          This. It’s a cute trick but not one that is particularly more useful than auto ymd {2021, January, 23};, especially since there’s plenty of countries out there that tend to use things other than / as a date separator.

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          xigoi avatar xigoi 5 months ago | link

          How does it hide control flow? An operator is just a different way to write a function.

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        snej avatar snej 5 months ago | link

        It’s nice syntax, but a bit over engineered IMO. How often does one need to construct Gregorian calendar dates this way? Regular struct declaration would look nearly as good.

        The / operator for concatenating filesystem paths is great, though.

      3. mort avatar mort 5 months ago | link

        [Comment removed by author]

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      owl avatar owl 5 months ago | link

      Could you combine it with user-defined literals like 2021_year and 23_day for even more suffering fun?

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      xfbs avatar xfbs 5 months ago | link

      I think this is a very impressive use of operator overloading in C++. The only criticism I have is that it seems to be somewhat overengineered: would it not be simpler to just allow something like yyyy/mm/dd?

      Now they had to introduce many possible combinations of ordering for questionable benefit:

      std::chrono::year_month(y, m)
std::chrono::year_month(y, std::chrono::month(m))
std::chrono::month_day(m, d)
std::chrono::month_day(m, std::chrono::day(d))
std::chrono::month_day(std::chrono::month(m), d)
std::chrono::month_day_last(m)
std::chrono::month_day_last(std::chrono::month(m))
std::chrono::month_weekday(m, wdi)
std::chrono::month_weekday(std::chrono::month(m), wdi)
std::chrono::month_weekday_last(m, wdl)
std::chrono::month_weekday_last(std::chrono::month(m), wdl)
std::chrono::year_month_day(ym.year(), ym.month(), d)
std::chrono::year_month_day(ym.year(), ym.month(), std::chrono::day(d))
std::chrono::year_month_day(y, md.month(), md.day())
std::chrono::year_month_day(std::chrono::year(y), md.month(), md.day())
std::chrono::year_month_day_last(ym.year(), std::chrono::month_day_last(ym.month()))
std::chrono::year_month_day_last(y, mdl)
std::chrono::year_month_day_last(std::chrono::year(y), mdl)
std::chrono::year_month_weekday(ym.year(), ym.month(), wdi)
std::chrono::year_month_weekday(y, mwd.month(), mwd.weekday_indexed())
std::chrono::year_month_weekday(std::chrono::year(y), mwd.month(), mwd.weekday_indexed())
std::chrono::year_month_weekday_last(ym.year(), ym.month(), wdl)
std::chrono::year_month_weekday_last(y, mwdl.month(), mwdl.weekday_last())
std::chrono::year_month_weekday_last(std::chrono::year(y), mwdl.month(), mwdl.weekday_last())

      I understand that everyone wants dd/mm/yyyy and US-Americans would like mm/dd/yyyy, so a good compromise may be to please nobody (like the UTC acronym) and keep code simpler.

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        Orva avatar Orva 5 months ago | link

        I thought that pretty much only US locale has / as date seperator (and we non-us peeps mainly use dot or dash). So that DD/mm/yyyy is monstrosity?

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          dz4k avatar dz4k 5 months ago | link

          I was taught all three were acceptable in my Turkish class (in a Turkish school (as a Turkish person (in Turkey))). So that’s at least two countries that use slashes as date separators.

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          david_chisnall avatar david_chisnall 4 months ago | link

          That ordering (little endian, stashes as separators) is also common in the UK, though for any formal use I prefer the ISO ordering (big endian, hyphens as separators). As long as I don’t have to deal with the weird middle-endian US format, I’m happy.

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          gerikson avatar gerikson edited 5 months ago | link

          According to Wikipedia French dates are written as DD/mm/yyyy.

          In informal usage in Sweden, the format DD/mm is sometimes used: “styrelsemötet är planerat till 7/5”.