opConcatAll?

[Steven Schveighoffer]

On 7/2/20 3:18 PM, jmh530 wrote:
> On Thursday, 2 July 2020 at 18:40:21 UTC, Steven Schveighoffer wrote:
>>> [snip]
>>>
>>> With a few small changes, you could just as easily have written
>>>
>>> int[] newArr;
>>> newArr[] = [0, 0, 0] + arr[] + [4, 5, 6];
>>>
>>> which is similar to the traditional type of problem that expression 
>>> templates were designed to solve.
>>
>> Hm.. I think you misunderstand the example.
>>
> 
> I think I understand the example, but I may not have made my point clear 
> enough...
> 
> You are concerned about a ~ b ~ c and avoiding unnecessary allocations.
> 
> Expression templates are concerned with problems like a + b + c and 
> avoiding the use of unnecessary temporaries.
> 
> They seem like similar problems to me. Temporaries and allocations are 
> obviously different, but the structure of the problem is similar. You 
> yourself note that "most of the allocations as temporaries".
> 
> If my point makes sense, then the implication is that this is a problem 
> that is not unique to concatenation and also applies to the mathematical 
> operators, in their own way.

OK, I see what you are saying. And yes, a generalized mechanism to 
handle this would be useful for both avoiding allocations and avoiding 
temporaries (among other things).

Nick's idea is pretty good for both.

-Steve