Operations
Iteration
C++11: recursion
riptutorial Iterating over a parameter pack
Often, we need to perform an operation over every element in a variadic template parameter pack. There are many ways to do this, and the solutions get easier to read and write with C++17. Suppose we simply want to print every element in a pack. The simplest solution is to recurse:
#include <iostream>
void print_all()
{
// base case
std::cout << std::endl;
}
template<class T, class ... Ts>
void print_all(T const &first, Ts const &... rest)
{
std::cout << first << " ";
print_all(rest...);
}
template<class ...Args>
void g(Args ...args)
{
print_all(args...);
}
template<class ...Args>
void f(Args ... args)
{
// auto lm = [&, args ...] { return g(args...);};
// lm();
print_all(args...);
}
int main()
{
f("hello", "world");
}
// g++ --std=c++11 test.cpp
NOTE: 输出如下:
hello world
C++17: fold expression
参见./C++17-Fold-expression章节。
Len
参见:
1、参见 ./sizeof-parameter-pack 章节
Examples
std::declval expansion
C++ named requirements: Callable:
INVOKE<R>(f, std::declval<ArgTypes>()...)
Adder
参见../../eli.thegreenplace-Variadic-templates-in-C++。
tprintf
参见 cppreference Parameter pack(since C++11)。
All
参见 ./C++17-Fold-expression。
TODO
stackoverflow Variadic template pack expansion
iterating-over-a-parameter-pack
https://riptutorial.com/cplusplus/example/3208/iterating-over-a-parameter-pack