opDollar

[Bill Baxter]

On Tue, Sep 9, 2008 at 9:37 AM, Andrei Alexandrescu
<SeeWebsiteForEmail at erdani.org> wrote:
> Denis Koroskin wrote:
>> 4) We need some way of supporting dollar notation in user containers. The
>> hack of using __dollar is bad (although it works).
>
> It doesn't work for multiple dimensions. There should be an opDollar(uint
> dim) that gives the library information on which argument count it occured
> in. Consider:
>
> auto x = matrix[$-1, $-1];
>
> Here the dollar's occurrences have different meanings. A good start would be
> to expand the above into:
>
> auto x = matrix[matrix.opDollar(0)-1, matrix.opDollar(1)-1];
>

Actually __dollar can be made to work with a bit of overhead.  Make
__dollar be a particular struct type, say EndRelativeIndex, that holds
an integer offset and has overloaded opAdd and opSub, then make
overloads for Matrix opIndex that accept that struct type.  A
"sufficiently smart compiler" could probably even get rid of the
overhead.

But all that trickery would be unnecessary if opDollar existed and
behaved as you suggest.

--bb