complement to $

[Steven Schveighoffer]

On Mon, 17 May 2010 11:02:05 -0400, Ellery Newcomer  
<ellery-newcomer at utulsa.edu> wrote:

> On 05/14/2010 08:20 AM, Steven Schveighoffer wrote:
>> Currently, D supports the special symbol $ to mean the end of a
>> container/range.
>>
>> However, there is no analogous symbol to mean "beginning of a
>> container/range". For arrays, there is none necessary, 0 is always the
>> first element. But not all containers are arrays.
>>
>> I'm running into a dilemma for dcollections, I have found a way to make
>> all containers support fast slicing (basically by imposing some
>> limitations), and I would like to support *both* beginning and end  
>> symbols.
>>
>> Currently, you can slice something in dcollections via:
>>
>> coll[coll.begin..coll.end];
>>
>>
>> -Steve
>
> Does your collections library allow for code like
>
> coll[coll.begin + 1 .. coll.end]

No.  begin and end return cursors, which are essentially non-movable  
pointers.

The only collection where adding an integer to a cursor would be feasible  
is ArrayList, which does support slicing via indexes (and indexes can be  
added/subtracted as needed).

Note, I'm not trying to make slicing dcollections as comprehensive as  
slicing with arrays, I'm just looking to avoid the verbosity of re-stating  
the container's symbol when specifying the beginning or end.  In all  
dcollections containers, one can always slice where one of the endpoints  
is begin or end.

I probably should at least add opDollar to ArrayList...

-Steve