Is there an easy way to mimic generics with an accept method of a visitor pattern?

[Paul Backus]

On Thursday, 18 February 2021 at 14:26:37 UTC, vitamin wrote:
>
> Or combination of discriminate uninons and classes:
>
> /+dub.sdl:
> dependency "sumtype" version="~>0.10.0"
> +/
> import std.stdio;
>
> import sumtype;
>
> alias Expression = SumType!(
>     ExprValue,
>     ExprBinary,
>     ExprUnary
> );
>
> class Expr{
>     abstract Expression expression()pure nothrow @safe @nogc;
>
> }

I don't see what this buys you compared to sticking with one or 
the other, but you are correct that it is technically possible.