Re: [boost] [units] Interest in UDLs (e.g. _kg) for units?

Subject: Re: [boost] [units] Interest in UDLs (e.g. _kg) for units?
From: Erik Erlandson (eje_at_[hidden])
Date: 2014-08-28 08:44:43

It might be nice to support non-abbreviated varations:

_milligram, _kiloton, _megabyte, etc.

As an aside, there is a "derived" unit for just grams defined in there somewhere, maybe as part of the CGS subsystem?

----- Original Message -----
> Hi all,
> 
> I was wondering if there is any interest in adding User-Defined Literals
> (UDLs) to Boost.Units.
> 
> IMO, it could simplify some code and improve code readability in some cases.
> For example instead of writing (it's a somehow artificial example)
>     5.34 * si::milli * si::kilogram;
>     1234 * si::kilogram;
> one would write
>     5.34_g;
>     1234_kg;
> 
> I propose to add this feature for compatible compilers (where
> BOOST_NO_CXX11_USER_DEFINED_LITERALS is not defined).
> The user would have to pull corresponding namespace (let's call it `udl`)
> to use it, for example
>     using namespace boost::units::systems::si::udl; // bring _kg, _km, ...
> into scope
> 
> What are your feelings about it?
> 
> In the first place, I would go for `operator ""` taking as arguments
> `unsigned
> long long` and `long double`.
> Later, one could think about the one taking a `const char *` argument which
> would provide a quantity with an underlying type of arbitrary precision
> (like boost::multiprecision::cpp_int).
> 
> Regards,
> 
> Marek Kurdej
> --
> Ph.D. candidate
> 
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