std::piecewise_construct_t
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| Dclar dans l'en-tte <utility>
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struct piecewise_construct_t { }; |
(depuis C++11) | |
std::piecewise_construct_t est un type struct vide balise utilise pour lever l'ambigut entre les diffrentes fonctions qui prennent deux arguments tuple .
Original:
std::piecewise_construct_t is an empty struct tag type used to disambiguate between different functions that take two tuple arguments.
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Les surcharges qui ne std::piecewise_construct_t utiliser supposer que chaque argument tuple devient l'lment d'une paire. Les surcharges qui utilisent std::piecewise_construct_t supposer que chaque argument tuple est utilis pour construire, par morceaux, un nouvel objet du type spcifi, qui deviendra l'lment de la paire .
Original:
The overloads that do not use std::piecewise_construct_t assume that each tuple argument becomes the element of a pair. The overloads that use std::piecewise_construct_t assume that each tuple argument is used to construct, piecewise, a new object of specified type, which will become the element of the pair.
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Exemple
#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);
}
Rsultat :
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
Voir aussi
(C++11) |
un objet de piecewise_construct_t type utilis pour lever l'ambigut des fonctions pour la construction par morceaux Original: an object of type piecewise_construct_t used to disambiguate functions for piecewise construction The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (constante) |