std::piecewise_construct_t
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definiert in Header <utility> | ||
struct piecewise_construct_t {}; | (seit C++11) | |
std::piecewise_construct_t is an empty struct tag type used to disambiguate between different functions that take two tuple arguments.
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.
[Bearbeiten]Beispiel
#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);}
Output:
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
[Bearbeiten]Siehe auch
(C++11) | ein Objekt vom Typ piecewise_construct_t verwendet, um Funktionen für stückweise Konstruktion eindeutig zu machen 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. (konstanten) |
