Sorry, I just love templates, AAs and mixins :)

[Saaa]

public void addToAA(char[] var_name, KT, ET)(KT key, ET element)
{
  mixin(ET.stringof~`[]* elements = key in `~var_name~`;`);
  if( elements == null )
  {
    ET[] temp;
    temp.length = 1;
    temp[0] = element;
    mixin(var_name~`[key] = temp;`);
  }
  else
  {
    (*elements).length = (*elements).length + 1;
    (*elements)[(*elements).length-1] = element;
  }
}