Proposal: Make [][x] and [][a..b] illegal (reserve for multidimensional

[Bill Baxter]

Dan wrote:
> Bill Baxter Wrote:
> 
>> Don Clugston wrote:> 
>> Another proposal would be to allow [..] as your slice an move on syntax, 
>> and keep the current meaning of [].
> 
> Jeepers, we already have $ as a shorthand for length.  Is 0..$ really too long?  Even an 11 dimensional array is legible with that.  11 dimensions is barely comprehensible to even the best mind.  Most folk can't even perceive 4.
> 
> x[0..$][0..$][0..$][0..$][0..$][0..$][0..$][0..$][0..$][0..$][0..$];

It looks very ugly to people used to working with the likes of Matlab 
and NumPy.

>> Also one thing not clear to me with your proposal is whether 
>> f[1..2][2..3][3..4] generates 3 opSlice calls or just 1 when applied to 
>> a user class.  I can see reasons for wanting both.  If you have a fixed 
>> dimension class that only allows integer slicing, then probably 1 
>> opSlice call with all 3 slices is the most useful.  If you have 
>> something representing a N-dimensional thing where N is runtime, and you 
>> allow for slicing with objects (like other N-dimsional arrays), then 3 
>> separate chained calls like f.opSlice(a).opSlice(b).opSlice(c) might be 
>> more useful to cut down on all the combinatorial explosion of possible 
>> combos of opSlice arguments.
>>
>> --bb
> 
> 
> Yeah, I tend to agree with using 3 separate opSlice calls.  But... we don't even need to create an opSlice method, do we?  Arrays already work wonderfully?  Doesn't:
> 
> [code]
> float[42][12][14] x;
> float[42][2][2] y;
> 
> y = x[0..$][1..2][3..4];
> [/code]
> That works, right?  and you can loop over it just like this?
> [code]
> for(int i = 0; i < x.length; i++)
> {
>    for(int j = 0; j < x[i].length; j++)
>    {
>    }
> }
> [/code]
> 
> I don't see the problem?

Aside from the unattractiveness of the syntax, there's a question of 
efficiency creating all those extra function calls and temp variables. 
If the compiler will make it all go away great, but I'm not counting on 
it, given that DMD can't even inline functions with loops.

--bb