Can I use memoize with a non-static struct method?

[Mengu]

On Tuesday, 26 December 2017 at 00:47:14 UTC, Marc wrote:
> something like this:
>
>> struct S {
>>   // variables...
>>   string doGen(int n) { return ""; }
>>   alias gen = memoize!doGen;
>> }
>
> The error I got is:
>
>> Error: need 'this' for 'doGen' of type 'string(int n)'
>
> I can't make doGen static because it access non-static struct 
> members... can I workaround this?

i don't want to mislead you and i don't know if this is somehow 
possible but what about some ufcs magic?


   string doGen(S s, int n) {
     return "hello ".repeat().take(n).join();
   }

   struct S {

     int x;

     auto gen() @property {
       return memoize!doGen(this, x);
     }

   }

   void main() {
     S s = S(5);
     s.gen.writeln;

     s.x = 10;
     s.gen.writeln;

     s.x = 15;
     s.gen.writeln;

     s.x = 20;
     s.gen.writeln;
}