opDollar and infinite slices on infinite ranges

[Philippe Sigaud]

On Wed, Jul 21, 2010 at 21:47, Simen kjaeraas <simen.kjaras at gmail.com>wrote:

>
> I wrote this indexing struct. Clearly not perfect, but it sorta does the
> right things:
>
> To use, make opSlice take an Index parameter, and call its opCall with the
> length
> of the container.


OK, it take the length and compute the result index, as in $/2+5, etc.
OK, I defined an opSlice(size_t i1, Index i2) {...} and it worked! Thanks
Simen !
In my case, I guess the Index is just there to be a sentinel value,
generated by __opdollar, as I for an infinite range, I do not have a length
to give it, I just want arithmetic operations on Index to always return an
Index.

Except... I cannot do that:  c[2..$+$] ... Ah, I get it: maybe like this:

Index opBinary( string op )( Index i ) const {
   Index result;
   result.dg = ( long value ) {
      mixin( "return dg( value ) " ~ op ~ " i(value);" );
    };
    return result;
}

I don't understand you opUnary code:

Index opUnary( string op )( ) {
   dg = ( long value ) {
       mixin( " auto tmp = dg( value ); tmp" ~ op ~ "; return tmp;" );
   };
   return this;
}

Shouldn't that be ;" ~ op ~ "tmp; return tmp;" ?


So, cool, that works. I'll just have to check if operations on 'infinite'
Index work as they should.



> Wish there was a way to make late-bound templates in D, as that
> could allow for different value types depending on usage.
> Hm, maybe there is a way, now that I think of it. I shall have to check in
> the future.
>
>
What do you mean?


Philippe
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