Add size function to alpaka::Vec

[mehmetyusufoglu]

This PR adds a static function to the alpaka::Vec. It is defined static so that it can be used with the type aliases as well.

[fwyzard]

please put an explicit return type.
I understand that the compiler can guess what it is, but the users shouldn't have to try and guess.

[SimeonEhrig]

Please copy the function signature from my PR #2415
This is the state of the art definition for C++20.

[fwyzard]

What is the different wrt #2415 ?

[mehmetyusufoglu]

Dim is not the correct name. This is a 1D static array and can be used for any reason. (Using Dim assumes Vec is used only to define dimensions of a grid, block or data.) 23 Eki 2024 Çar 23:28 tarihinde Andrea Bocci ***@***.***> şunu yazdı:

…

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[SimeonEhrig]

Dim is not the correct name. This is a 1D static array and can be used for any reason. (Using Dim assumes Vec is used only to define dimensions of a grid, block or data.) 23 Eki 2024 Çar 23:28 tarihinde Andrea Bocci @.> şunu yazdı:
…
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I disagree. We can compare alpaka::Vec with std::extents. std::extents has no explicit size but rank, what is the same like your Dim. If we use std::extents with std::mdspan, we have the function size() which returns the production of the values of each rank in the std::extents. See this example:

std::vector data(100, 0);
std::mdspan md(data.data(), std::extents{10, 10});

// output: 100
std::cout << md.size() << "\n";

// output:
// rank 0: 10
// rank 1: 10
for(auto i = 0; i < md.rank(); ++i){
    std::cout << "rank " << i << ": " << md.extent(i) << "\n"; 
}

Also the special case alpaka::Vec<int, alpaka::DimInt<1>> is the same like std::vector<int>. And in the case of std::vector size() will return the value of the one dimension.

Therefore is clear what is size() is doing. We can discuss, if we want to name the function rank() or dim() something else but size() is already used for a different function. For alpaka::Vec it is:

alpaka::Vec<int, alpaka::DimInt<1>> vec = {10};
std::cout << vec[0] << "\n"; // outputs the size 10
std::cout << vec.size() << "\n"; // outputs the size 10

alpaka::Vec<int, alpaka::DimInt<1>> vec2 = {10, 2};
std::cout << vec.size() << "\n"; // outputs the size 20
``

[SimeonEhrig]

What is the different wrt #2415 ?

By the way, I don't know @mehmetyusufoglu open the same PR again and didn't ask for changing the name in my PR.

[mehmetyusufoglu]

I have not seen your PR, sorry. Simeon Ehrig ***@***.***>, 24 Eki 2024 Per, 11:40 tarihinde şunu yazdı:

…

What is the different wrt #2415 <#2415> ? By the way, I don't know @mehmetyusufoglu <https://github.com/mehmetyusufoglu> open the same PR again and didn't ask for changing the name in my PR. — Reply to this email directly, view it on GitHub <#2416 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AUYXIJOMODUBCSOM4ZM26DLZ5C57NAVCNFSM6AAAAABQPR2EXWVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDIMZUG44DQOBXGI> . You are receiving this because you were mentioned.Message ID: ***@***.***>