just a short note:
now we can do:
(dmd 0.99)

int[] b = a[0..length-2];

where a is another array of int...


but isn't the 'length' ident redundant at all ? Python makes it implicit when the index is negative, so that a[0..-2] is a[0..length-2]. why dont we have it the same way ? it is very handy :)

On Fri, 20 Aug 2004 04:46:47 +0200, h3r3tic wrote:

> just a short note:
> now we can do:
> (dmd 0.99)
> 
> int[] b = a[0..length-2];
> 
> where a is another array of int...
> 
> but isn't the 'length' ident redundant at all ? Python makes it implicit when the index is negative, so that a[0..-2] is a[0..length-2]. why dont we have it the same way ? it is very handy :)

Its more explicit; tells the reader what we were intending to do.

It helps trap some mistakes...

   int x,y;

   y = calc_size(a, z);
   . . .
   x = y - 1;

   b = a[1..x];

But if for some reason 'y' was zero or lower, this would be an error. It might not go detected if -ve values were allowed in slices.

-- 
Derek
Melbourne, Australia
20/Aug/04 12:50:38 PM

Derek Parnell wrote:
> Its more explicit; tells the reader what we were intending to do.
> 
> It helps trap some mistakes...
> 
>    int x,y;
> 
>    y = calc_size(a, z);
>    . . .    x = y - 1;
> 
>    b = a[1..x];
> 
> But if for some reason 'y' was zero or lower, this would be an error. It
> might not go detected if -ve values were allowed in slices.
> 

ok, i get ur point. thanks :]

how about another thing though ? in python (yea, again ;]) i can say x[0:10:2] and that will create a sliced array with indexes 0, 2, 4, 6, 8, basically changing the stride of the slice. how bout that ? could be [a..b:c] or just [a..b..c] but i'd prefer the former

"h3r3tic" <h3r3tic@dev.null> wrote in message news:cg3omi$2p2q$1@digitaldaemon.com...
> just a short note:
> now we can do:
> (dmd 0.99)
>
> int[] b = a[0..length-2];
>
> where a is another array of int...
>
>
> but isn't the 'length' ident redundant at all ? Python makes it implicit when the index is negative, so that a[0..-2] is a[0..length-2]. why dont we have it the same way ? it is very handy :)

This is a common request. One reason it isn't done is it requires a runtime check, and people really like their arrays to be fast!

In article <cg3rb4$2qij$1@digitaldaemon.com>,
 h3r3tic <h3r3tic@dev.null> wrote:

> ok, i get ur point. thanks :]
> 
> how about another thing though ? in python (yea, again ;]) i can say x[0:10:2] and that will create a sliced array with indexes 0, 2, 4, 6, 8, basically changing the stride of the slice. how bout that ? could be [a..b:c] or just [a..b..c] but i'd prefer the former

Slices return a pointer to a contiguous block of memory located inside the array you sliced.  It doesn't allocated any new memory, it's just a pointer and a length.   At least that's my understanding.

Sha Chancellor wrote:
> In article <cg3rb4$2qij$1@digitaldaemon.com>,
>  h3r3tic <h3r3tic@dev.null> wrote:
> 
> 
>>ok, i get ur point. thanks :]
>>
>>how about another thing though ? in python (yea, again ;]) i can say x[0:10:2] and that will create a sliced array with indexes 0, 2, 4, 6, 8, basically changing the stride of the slice. how bout that ? could be [a..b:c] or just [a..b..c] but i'd prefer the former
> 
> 
> Slices return a pointer to a contiguous block of memory located inside the array you sliced.  It doesn't allocated any new memory, it's just a pointer and a length.   At least that's my understanding.

Sure, but there was a discussion going around some time earlier (relative to my old post) proposing interleaved arrays (even for multidimensional arrays) and this would just fit nicely with that concept.