Units of Measurement Library: units-d

[ag0aep6g via Digitalmars-d-announce]

On 01.04.2016 01:58, Nordlöw wrote:
> https://github.com/nordlow/units-d

 From there:

>  * Example:
>  * ---
>  * alias BaseUnit!("Ampere", "A") Ampere;
>  * enum ampere = Ampere.init;
>  * // or
>  * enum ampere = baseUnit!("Ampere", "A");
>  * ---

I dislike that the type depends only on the given name. This effectively 
means that the names are in a global namespace.

For example:

----
import experimental.units;

struct A
{
     alias BaseUnit!("Ampere", "A") Ampere;
     enum ampere = Ampere.init;
}

struct B
{
     alias BaseUnit!("Ampere", "A") Ampere;
     enum ampere = Ampere.init;
}
----

A.Ampere and B.Ampere are the same type here. I think it would be more 
useful if they weren't. When two unrelated sources define a new unit 
with the same name, then they shouldn't be compatible. Think of all the 
different kinds of pounds and miles there used to be in the world.

I can't think of a truly nice way to accomplish this, though. As far as 
I see, it needs a mixin of some kind.

Like this, for example:

----
enum string baseUnit = q{
     {
         static struct BaseUnit {/* ... */}
         return BaseUnit.init;
     }()
};

struct A
{
     enum ampere = mixin(baseUnit);
}

struct B
{
     enum ampere = mixin(baseUnit);
}

static assert(!is(typeof(A.ampere) == typeof(B.ampere)));
----