Proposal: __traits(code, ...) and/or .codeof

[F i L]

Timon Gehr wrote:
> We have the macro keyword. I envision something like:
>
> macro replaceAggregate(macro newAggregate, macro loop : 
> foreach(x; aggr){statements}, macro x, macro aggr, macro 
> statements) {
>     foreach(x; newAggregate){statements}
> }
>
> void main(){
>     int[] a = [1,2,3];
>     int[] b = [2,3,4];
>     replaceAggregate(b, foreach(x;a){writeln(x);});
> }
>
> (The syntax looks horrible, but you get the idea: AST walking 
> by pattern matching)

This looks substantially more complicated than what I had in 
mind. I think it's a great idea, but something that could be 
added after the initial functionality was there.


> macro until(macro condition, string str){
>     while(!condition){
>         mixin(str); // string and mixin not strictly necessary,
>                     // maybe enable the feature on macro params 
> too
>     }
> }
>
> void main(){
>     bool done = false;
>     int x;
>     until(done){
>         done = foo(x++);
>     }
> }
>
> This is just a very rough sketch though, we would need a much 
> more refined design. I think getting the symbol scoping right 
> is most important.

I'm a bit confused about what's actually going on here, but it 
certainly looks interesting. What exactly is being passed to 
"string str" in the macro?