std.v2 builder pattern replacement

[monkyyy]

On Wednesday, 27 July 2022 at 09:15:28 UTC, FeepingCreature wrote:
> This only works with constants;

```d
auto withMe(string mixin_,Me,T...)(Me me,T arg){
	with(me){
		mixin(mixin_);
	}
	import std.algorithm;
	static if(!mixin_.canFind("return")){
		return me;
	}
}
struct foo{
	float f;
	int uselessfield=1337;
	bool b;
}
alias biuldfoo=withMe!(q{f=arg[1];b=arg[0];},foo,bool,float);
void main(){
	import std.stdio;
	bool t=true;
	float fourtwenty=4.20;
	foo().withMe!q{f=arg[1];b=arg[0];}(t,fourtwenty).writeln;
	foo().biuldfoo(t,fourtwenty).writeln;
}```