auto arr = [1, 2, 3] should be a static array, not a GC allocated array

[Don Allen]

On Saturday, 23 July 2022 at 17:51:34 UTC, ryuukk_ wrote:
> On Saturday, 23 July 2022 at 17:37:04 UTC, Don Allen wrote:
>> On Saturday, 23 July 2022 at 15:09:11 UTC, ryuukk_ wrote:
>>> On Saturday, 23 July 2022 at 14:56:48 UTC, Don Allen wrote:
>>>> Personally, I hope Walter ignores this conversation. I think 
>>>> the current syntactic distinction (presence or absence of a 
>>>> constant length) between static and dynamic arrays is fine 
>>>> and whether a dynamic array is gc-allocated or 
>>>> stack-allocated seems to me to be a compiler optimization 
>>>> issue. I would think that if the compiler can prove that the 
>>>> array doesn't need to be re-allocated due to expansion and 
>>>> if allocation on the stack provides a sufficient lifetime, 
>>>> then it can stack allocate. And we should only care whether 
>>>> dmd does this optimization if it becomes clear that it is 
>>>> important in a lot of use cases, which I doubt.
>>>
>>> I would be fine if the distinction was made by the compiler, 
>>> but in critical performance scenarios, i don't want to gamble 
>>> wether the compiler will optimize something or not
>>>
>>> I want to make sure that my intent is perfectly understood by 
>>> the compiler
>>>
>>> I don't want any ambiguity, when i write the code, and more 
>>> importantly when i read it
>>>
>>> "Oh it is `auto arr = [1, 2, 3]` will it be stack allocated? 
>>> hmm idk, let me decypher this whole algorithm again`"
>>
>> If you don't want any ambiguity and want to be sure your array 
>> is stack-allocated, then
>> say so explicitly
>> ````
>> int arr[3]={1,2,3}
>> ````
>>
>> rather than using auto.
>>>
>>>> And regarding that optimization, as hardware has gotten 
>>>> faster and faster (remember the Cray 1 "supercomputer"? It 
>>>> had an 80 mhz clock frequency), we have become more and more 
>>>> guilty of premature optimization. The flip side of that is 
>>>> that is the amount of software we all use daily that is 
>>>> written in languages like Python, Javascript or PHP that are 
>>>> perhaps 2 orders of magnitude slower than D and still 
>>>> provide adequate performance even on our phones.
>>>>
>>>> My opinion.
>>>>
>>>> /Don
>>>
>>> Not everyone develop for High End devices
>>>
>>> Some people are fine paying more $$$ for higher Cloud 
>>> instance tier, some are not
>>>
>>> I personally stick to the cheapest to host my stuff, and my 
>>> care made me save lot of money, and my programs are all fast, 
>>> no compromise, and the language shouldn't cater to the lower 
>>> common denominator, the developer should make that choice
>>
>> And the developer *can* make that choice as the language 
>> stands today.
>>
>> As for the gc-allocated vs static optimization, that only 
>> applies to dynamic arrays and, as I said, it is far from clear 
>> how important that is in the grand scheme of things, even on 
>> cheap hardware. But if it's important to you that your arrays 
>> be stack-allocated, use static arrays, specified explicitly 
>> (not by using 'auto). And if passing by value is a problem for 
>> you, pass pointers. What you want is in the language now.
>
>
> I'm not asking how to write a static array in D, i'm asking to 
> improve how we write them
>
> I suggest you check the motive in the DIP 
> https://github.com/dlang/DIPs/blob/master/DIPs/other/DIP1039.md

I'm aware of that. And I think what is being suggested is trivial 
syntactic sugar that fixes something that ain't broke.