Templated operator overloading

[aliak]

On Wednesday, 22 August 2018 at 11:58:25 UTC, XavierAP wrote:
> I've been trying some things to template operator overloads. 
> The reason is that I want very similar code for different 
> types, but I can't use polymorphism, as they're structs rather 
> than classes. Perhaps this choice is not as advantageous as I 
> think, and I may change this design from structs to classes, or 
> else the code duplication would be small and never subject to 
> change. But now I'm just trying for the sake of learning to 
> find out what works or not in terms of templated operator 
> overloading, and whether the reason something doesn't work is 
> by design and if mentioned in the specification, or just an 
> arbitraty result of some unspecified parsing/lowering step 
> order, or it depends on the compiler (I'm using dmd).
>
> [...]

"void opOpAssign(string op, T)(ref Tthis, const ref T x)" looks 
like the wrong signature for opOpAssign. THink it needs to be:

void opOpAssign(string op, T)(const ref T x)

Then:

mixin template operator!
{
	void opOpAssign(string op, T)(const ref T x)
	{
		writeln(this, op, x);
	}
}

struct S1
{
	mixin operator;
}
struct S2
{
	mixin operator;
}

Cheers,
- Ali