DIP Mir1 Draft: Variadic template parameters with the same time.

Problem Most ndslice API accepts variadic list of integers. The following code example shows how `slice` and `[a, b, c]` can generate 64 identical functions each. ``` // (1, 1U, 1UL, 1L) x // (2, 2U, 2UL, 2L) x // (3, 3U, 3UL, 3L) = 4 ^^ 3 = 64 identical variants auto cube = slice!double(1, 2, 3); size_t i; sizediff_t j; int k; uint p; // 64 identical variants for 64-bit with i, j, k, p auto v = cube[i, j, k]; ``` ------------------------ Solution T[] can be added to a template variadic name. ``` void foo(size_t[] Index...)(Indexes index) { ... } ```

On Thursday, 29 September 2016 at 17:24:55 UTC, Ilya Yaroshenko wrote: > Problem > > Most ndslice API accepts variadic list of integers. > The following code example shows how `slice` and `[a, b, c]` > can generate 64 identical functions each. > > ``` > // (1, 1U, 1UL, 1L) x > // (2, 2U, 2UL, 2L) x > // (3, 3U, 3UL, 3L) = 4 ^^ 3 = 64 identical variants > auto cube = slice!double(1, 2, 3); > > size_t i; > sizediff_t j; > int k; > uint p; > // 64 identical variants for 64-bit with i, j, k, p > auto v = cube[i, j, k]; > ``` > ------------------------ > > Solution > > T[] can be added to a template variadic name. > > ``` > void foo(size_t[] Index...)(Indexes index) > { > ... > } > ``` This description does not tell me anything.

On Thursday, 29 September 2016 at 17:56:59 UTC, Stefan Koch wrote: >> Solution >> >> T[] can be added to a template variadic name. >> >> ``` >> void foo(size_t[] Index...)(Indexes index) >> { >> ... >> } >> ``` > > This description does not tell me anything. Current template argument can be declared as `(Index...)`. The solutions just allows to specify the type `(size_t[] Index...)`

On Thursday, 29 September 2016 at 18:37:36 UTC, Ilya Yaroshenko wrote: > On Thursday, 29 September 2016 at 17:56:59 UTC, Stefan Koch wrote: >>> Solution >>> >>> T[] can be added to a template variadic name. >>> >>> ``` >>> void foo(size_t[] Index...)(Indexes index) >>> { >>> ... >>> } >>> ``` >> >> This description does not tell me anything. > > Current template argument can be declared as `(Index...)`. > The solutions just allows to specify the type `(size_t[] Index...)` I think we already have typesafe variadics. What do you want to change ?

On 09/29/2016 02:37 PM, Ilya Yaroshenko wrote: > On Thursday, 29 September 2016 at 17:56:59 UTC, Stefan Koch wrote: >>> Solution >>> >>> T[] can be added to a template variadic name. >>> >>> ``` >>> void foo(size_t[] Index...)(Indexes index) >>> { >>> ... >>> } >>> ``` >> >> This description does not tell me anything. > > Current template argument can be declared as `(Index...)`. > The solutions just allows to specify the type `(size_t[] Index...)` This feature exists. What am I missing? -- Andrei

On Thursday, 29 September 2016 at 18:49:45 UTC, Stefan Koch wrote: > On Thursday, 29 September 2016 at 18:37:36 UTC, Ilya Yaroshenko wrote: >> On Thursday, 29 September 2016 at 17:56:59 UTC, Stefan Koch wrote: >>>> Solution >>>> >>>> T[] can be added to a template variadic name. >>>> >>>> ``` >>>> void foo(size_t[] Index...)(Indexes index) >>>> { >>>> ... >>>> } >>>> ``` >>> >>> This description does not tell me anything. >> >> Current template argument can be declared as `(Index...)`. >> The solutions just allows to specify the type `(size_t[] Index...)` > > I think we already have typesafe variadics. Only for runtime arguments. > What do you want to change ? `(Index...)` -> `(size_t[] Index...)` // this is about template arguments, not runtime

On 09/29/2016 02:53 PM, Ilya Yaroshenko wrote: > `(Index...)` -> `(size_t[] Index...)` // this is about template > arguments, not runtime What is the drawback of taking Index... and constraining it with a template constraint (all must be integral)? We use that in a few places in Phobos. -- Andrei

On 9/29/16 2:49 PM, Stefan Koch wrote: > On Thursday, 29 September 2016 at 18:37:36 UTC, Ilya Yaroshenko wrote: >> On Thursday, 29 September 2016 at 17:56:59 UTC, Stefan Koch wrote: >>>> Solution >>>> >>>> T[] can be added to a template variadic name. >>>> >>>> ``` >>>> void foo(size_t[] Index...)(Indexes index) >>>> { >>>> ... >>>> } >>>> ``` >>> >>> This description does not tell me anything. >> >> Current template argument can be declared as `(Index...)`. >> The solutions just allows to specify the type `(size_t[] Index...)` > > I think we already have typesafe variadics. > What do you want to change ? typesafe variadics as runtime parameters, not compile-time parameters. -Steve

September 29, 2016

Re: DIP Mir1 Draft: Variadic template parameters with the same time.

Posted by Ilya Yaroshenko
in reply to Andrei Alexandrescu

Permalink

Ilya Yaroshenko

Posted in reply to Andrei Alexandrescu

Permalink

On Thursday, 29 September 2016 at 18:53:26 UTC, Andrei Alexandrescu wrote:
> On 09/29/2016 02:37 PM, Ilya Yaroshenko wrote:
>> On Thursday, 29 September 2016 at 17:56:59 UTC, Stefan Koch wrote:
>>>> Solution
>>>>
>>>> T[] can be added to a template variadic name.
>>>>
>>>> ```
>>>> void foo(size_t[] Index...)(Indexes index)
>>>> {
>>>>     ...
>>>> }
>>>> ```
>>>
>>> This description does not tell me anything.
>>
>> Current template argument can be declared as `(Index...)`.
>> The solutions just allows to specify the type `(size_t[] Index...)`
>
> This feature exists. What am I missing? -- Andrei

No, it does not
---
, void foo(size_t[] I...)(I i)
{
	
}

void main()
{
	foo(1, 2, 3);
}
---
/d812/f719.d(1): Error: found '...' when expecting ')'
/d812/f719.d(1): Error: found ')' when expecting '('
/d812/f719.d(1): Error: basic type expected, not (
/d812/f719.d(1): Error: function declaration without return type. (Note that constructors are always named 'this')
/d812/f719.d(2): Error: found '{' when expecting ')'
/d812/f719.d(4): Error: semicolon expected following function declaration
/d812/f719.d(4): Error: unrecognized declaration

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