DMD 0.177 release [Length in slice expressions]

[Bill Baxter]

Oskar Linde wrote:
> == Quote from Bill Baxter (dnewsgroup at billbaxter.com)'s article
>> Oskar Linde wrote:
>>> Bill Baxter wrote:
>>>> After trying to write a multi-dimensional array class, my opinion is
>>>> that D slice support could use some upgrades overall.
>>> I'd be very interested in looking at what you've come up with. With my
>>> own implementation of a multi-dimensional array type a couple of months
>>> ago, I came to the same conclusion. I posted about it in:
>>>
>>> news://news.digitalmars.com:119/edrv0n$hth$1@digitaldaemon.com
>>> http://www.digitalmars.com/d/archives/digitalmars/D/announce/4717.html
>>>
>>>> What I'd like to see:
>>>>
>>> --MultiRange Slice--
>>>> * A way to have multiple ranges in a slice, and a mix slice of and
>>>> non-slice indices:
>>>>     A[i..j, k..m]
>>>>     A[i..j, p, k..m]
>>> (snip)
>>>>     A[0..$,3..$]
>>> Yes, I would too. It is quite frustrating having the syntax in the
>>> language but not being allowed to utilize it... :)
>>>
>>> I work around this by instead using a custom slice syntax instead:
>>>
>>> A[range(i,j), range(k,m)]
>>> A[range(i,j), p, range(k,m)]
>>> A[range(0,end), range(3..end)]
>>> A[end-1, p % end]
>> Yeh, that's similar to what I'm doing too.  But it's pretty ugly.  So I
>> guess that means you're using opIndex for everything and leaving opSlice
>> alone.
> 
> Yes. Apart from the no-argument opSlice and opSliceAssign, that I overload
> with the same meaning as for the built in arrays. opSlice is not designed
> to support more than one dimension.
> 
>> Are you able to have ranges return arrays and specific indexes
>> return scalar values that way?
> 
> Yes.
> 
>> That seems to me a big reason for having
>> opSlice exist in the first place.  The .. in the brackets not only means
>> you're slicing, it also means the function should return another array,
>> versus returning an element.  That seems like a nice distinction to have
>> to me.
> 
> Yes, definitely. My implementation mimics the behavior of the D native
> array/slice type (T[]), but extended for multiple dimensions and strides.
> 
> So given Array!(2,int) A,  A[all,5] and A[5,all] are both Array!(1,int)
> of the 6-th row and column of A. A[5,5] is an int. Some other neat
> features made possible by strided arrays are for instance A.diag, that
> returns the 1-dimensional diagonal of the array, so eg:
> 
> A[] = 0;
> A.diag[] = 1;
> 
> would construct the unit matrix.
> 

Sounds great.  Is your code available anywhere?

--bb