C++ Template Parameter Packs with sequence

C++ Template Parameter Packs with sequence

Simple Explanation

sequence<x,x,x> is a template that holds a compile-time list of integer values. It's like a

tuple but for numbers only, and the values are fixed at compile time. It's commonly used in

template metaprogramming to pass multiple integer parameters to other templates.

Simple Usage Example

.

#include <iostream>

// A simple sequence template that holds compile-time integers

template<int... Values>

struct sequence {

static constexpr int size = sizeof...(Values);

// Function to print all values

static void print() {

((std::cout << Values << " "), ...); // C++17 fold expression

std::cout << std::endl;

}

};

// Template that uses sequence to create arrays

template<typename T, int... Dims>

class MultiArray {

private:

static constexpr int total_size = (Dims * ...); // multiply all dimensions

T data[total_size];

public:

MultiArray() {

std::cout << "Created array with dimensions: ";

((std::cout << Dims << "x"), ...);

std::cout << " = " << total_size << " elements" << std::endl;

}

static constexpr int get_total_size() { return total_size; }

};

int main() {

// Create sequences with different values

sequence<1, 8> block_warps; // 1 block, 8 warps

sequence<16, 16, 8> tensor_dims; // 16x16x8 tensor

sequence<2, 4, 8, 16> powers_of_2; // sequence of powers

std::cout << "Block warps: ";

block_warps.print(); // Output: 1 8

std::cout << "Tensor dims: ";

tensor_dims.print(); // Output: 16 16 8

std::cout << "Powers of 2: ";

powers_of_2.print(); // Output: 2 4 8 16

// Use sequence values as template parameters

MultiArray<float, 10, 20> matrix2d; // 10x20 = 200 elements

MultiArray<int, 4, 4, 4> tensor3d; // 4x4x4 = 64 elements

return 0;

}

..

Output:

  Block warps: 1 8

  Tensor dims: 16 16 8

  Powers of 2: 2 4 8 16

  Created array with dimensions: 10x20x = 200 elements

  Created array with dimensions: 4x4x4x = 64 elements

Thank you. 🙏