Use classes as keys in associative array

[JN via Digitalmars-d-learn]

Is it possible to use different class instances as keys for 
associative array, but compare them by the contents? I tried to 
override opEquals but it doesn't seem to work. Basically I'd like 
this code to work. I know structs would work but I can't use 
structs for this):

import std.stdio;
class Name
{
    string s;

    this(string s)
    {
        this.s = s;
    }
}

void main()
{
    Name n1 = new Name("John");
    Name n2 = new Name("John");

    int[Name] ages;
    ages[n1] = 50;

    assert(ages[n2] == 50);
}