Special Code String for mixins

[Jonathan Marler]

On Wednesday, 15 March 2017 at 13:50:28 UTC, Inquie wrote:
> I hate building code strings for string mixins as it's very 
> ugly and seems like a complete hack.
>
> How bout, instead, we have a special code string similar to a 
> multiline string that allows us to represent valid D code. The 
> compiler can then verify the string after compilation to make 
> sure it is valid D code(since it ultimately is a compile time 
> constant).
>
> e.g.,
>
> string s = "smile";
> enum code1 = @#
> void happyCode = "Makes me @@s@@";
> #@
>
> enum code2 = code1 ~ @#
> int ImThisHappy = @@s.length@@;
> #@
>
> mixin(code);
>
> or
>
> mixin(code.stringof); // possible to convert code string to a 
> string and vice versa.
>
>
> or whatever syntax one thinks is better. The point is that the 
> code string is specified different and then is no longer 
> ambiguous as a normal string. Compilers and IDE's can make more 
> informed decisions.
>
> There might be a much better way, but something should be done 
> to clean up this area of D. It is a mess to have to use string 
> building to create code. (it's amazingly powerful, but still a 
> mess)

I've got a PR for dmd (https://github.com/dlang/dmd/pull/7988) 
that implements "interpolated strings" which makes generating 
code with strings MUCH nicer, i.e.

string generateFunction(string attributes, string returnType, 
string name, string args, string body)
{
     import std.conv : text;
     return text(iq{
     // This is an interpolated string!
     $(attributes) $(returnType) $(name)($(args))
     {
         $(body)
     }
     });
}

// Let's use it:
mixin(generateFunction("pragma(inline)", "int", "add", "int a, 
int b", "return a + b;"));

assert(100 == add(25, 75));