DMD 0.177 release [Length in slice expressions]

[Andrei Alexandrescu (See Website for Email)]

Bill Baxter wrote:
> Andrei Alexandrescu (See Website For Email) wrote:
> 
>> But if we made "$" into an operator identifying the last element of 
>> _any_ array, which could refer to the last element of _the left-hand 
>> side_ array if we so want, then all of a sudden it becomes useful in a 
>> myriad of situations:
>>
>> int i = a[$ - 1]; // get last element
>> int i = a[$b - 1]; // get a's element at position b.length - 1
>> if (a[$ - 1] == x) { ... }
>> if ($a > 0) { ... }
>> if ($a == $b) { ... }
>> swap(a[0], a[$ - 1]); // swap first and last element
> 
> Please give some thought to the case where a and b are of types not 
> easily characterized by a single '.length'.  Matrix classes, or more 
> generally multidimensional array classes being the canonical examples. 
>  For those cases it is desirable to be able to have a '$' with different 
> meaning "per axis".

I did. The thing with language design is that it's easy to either
underdo or overdo it, and that where underdoing or overdoing starts is
highly subjective.

IMHO the current meaning of "$" is a good example of underdoing. The
"$expression" meaning "(expression).length" is (again IMHO) just right. I
use collection.size() all the time in C++, and scalar(@array) or $#array
all the time in Perl, inside and outside index expressions. So I'd be
happy to have that. Taking it to the next step of meaning any
subdimension of a multidimensional (or fractal, heh) structure is, IMHO,
overdoing because I can think of few use examples that are both frequent
enough and interesting enough.


Andrei