//module 1
template constArray(T) //This would be in another module
{
   struct Array
   {
       private T [] array;
             static Array opCall(T [] array)
       {
           Array t;
           t.array = array;
           return t;
       }
       T opIndex(int i) { return array[i]; }
       int length() { return array.length; }
   }
}

alias constArray!(int).Array constA;

//module 2

void test(constA array)
{
   int x = array[0];

//You just can't change the array variable (well at least not without force).

}

void main()
{
   int [] a;
   a ~= 10;
   a ~= 30;
   test(constA(a)); //Ok there's a small bit of extra typing -> if D only had automatic boxing....
}

-- 
-Anderson: http://badmama.com.au/~anderson/