Using .require for struct types

[Erdem Demir]

import std;

     struct A
     {
         double val;
         bool isBig;
     }


     void main() {
         alias DListOfA = DList!A;
         DListOfA[string] temp;
         A a = {2.0, true};

         DListOfA returnVal = temp.require("a", DListOfA());--> I 
wish I could use ref DListOfA here

         returnVal.insert(a);
         writeln(temp);
     }

On the reference page there is an example with class types only 
(https://dlang.org/spec/hash-map.html) but my type in associative 
array is a DList which is a struct type and that causes I am 
having a copy of my DList after require an operation. And of 
course my insert is happening to the copy and is not affecting to 
the associative array. ,


I wish I could use ref DListOfA returnVal = .... but we can't in 
D.

Can you please suggest alternatives?