Why doesn't `opAssign` work for my templated struct?

[kdevel]

On Friday, 8 November 2024 at 21:55:53 UTC, Liam McGillivray 
wrote:
> I am working on a library for making types representing units 
> of measurement. Base units [...]

> ```
> [...]
> enum Milligrams : BaseUnit!Milligrams;
> enum Millimoles : BaseUnit!Millimoles;
> [...]
> ```

Shouldn't (base) units be named in singular form?

> ```
> [...]
> 	Milligrams mass = Milligrams(20f);
> [...]
> ```

I would have expected something like

```
    Mass!milligram mass = Mass!milligram(20);
```

The variable mass represents a quantity measured in baseunits 
(milligrams). It does not represent the base unit. I'm afraid 
that your design will allow the assignment of amounts of 
substance to variables of "type" Milligrams.