Array expression for multi dimensional arrays

[Don]

Madhav wrote:
> == Quote from spir (denis.spir at gmail.com)'s article
>> On 03/23/2011 12:01 PM, Madhav wrote:
>>> Hi,
>>>
>>> I tried to do the following:
>>> auto arr = new int[2][2];
>>> arr[] = 1; // using array expressions
>>> // The above gives - Error: cannot implicitly convert expression (1) of type
>>> int  to const(int[2u][])
>>>
>>> This was the first step to try out if array arithmetic that worked with single
>>> dimensional arrays worked with multi-dimensional. I guess it does not.
>>>
>>> The immediate utility of this would be to cleanly do matrix algebra. Any ideas
>>> why powerful array expressions were not extended to multi dimensional arrays
>>> as well?
>>>
>>> Regards,
>>> Madhav
>> IIUC, you can do it level by level only:
>> unittest {
>>      int[3] a3;
>>      int[3][2] a32;
>>      a3[] = 1;
>>      a32[] = a3;
>>      assert(a32 == [[1,1,1], [1,1,1]]);
>> }
>> Note: in those assignments, [] is optional, but I consider this as a bug. Even
>> more since
>>     int[3] a3 = 1;	// works
>>     int[3][2] a32 = a3	// works not
>> denis
> 
> Yes i guessed that. My question was more to do with extending array expressions
> for multi dimensional arrays as well.
> Don't you think this should be provided by the language? It will ease out a lot of
> mathematical implementations

The problem is, that with the multi-dimensional case, you generally want 
STRIDED operations. These are much more complicated, and are much easier 
to implement in a library rather than in the core language.

Belongs in Phobos, no doubt about it. Currently waiting for the 
enhancement patch in bug 3474 to be applied.