My Kingdom For ...

[Jarrett Billingsley]

"Robert Fraser" <fraserofthenight at gmail.com> wrote in message 
news:fpjuh5$uai$1 at digitalmars.com...
> Darryl Bleau wrote:
>> opIndexConcat
>> opIndexConcatAssign

// Contrived, but shows the issue.
struct IntArray
{
    int[] mData;

    int opIndex(size_t idx)
    {
        return mData[idx];
    }
}

int[] realArray = [1, 2, 3];
realArray[0]++; // now contains [2, 2, 3]

IntArray a;
a.mData = [1, 2, 3];
a[0]++; // FAIL

In other words without these opIndexSomethingAssign overloads or ref returns 
it's impossible to make a user container type behave just like a built-in 
one.

(as an aside MiniD solves this by defining "a[0]++" to be "temp = a[0]; 
temp++; a[0] = temp;" but that's beside the point.)