std::piecewise_construct
De cppreference.com
<metanoindex/>
<tbody> </tbody> constexpr piecewise_construct_t piecewise_construct = std::piecewise_construct_t(); |
(desde C++11) | |
O std::piecewise_construct constante é uma instância de um tipo de vazio struct tag std::piecewise_construct_t.
Original:
The constant std::piecewise_construct is an instance of an empty struct tag type std::piecewise_construct_t.
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Exemplo
#include <iostream>
#include <utility>
#include <tuple>
struct Foo {
Foo(std::tuple<int, float>)
{
std::cout << "Constructed a Foo from a tuple\n";
}
Foo(int, float)
{
std::cout << "Constructed a Foo from an int and a float\n";
}
};
int main()
{
std::tuple<int, float> t(1, 3.14);
std::pair<Foo, Foo> p1(t, t);
std::pair<Foo, Foo> p2(std::piecewise_construct, t, t);
}
Saída:
Constructed a Foo from a tuple
Constructed a Foo from a tuple
Constructed a Foo from an int and a float
Constructed a Foo from an int and a float