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[英]C++ - Specify Overloaded Functor or Function When Passing To `std::function`
[英]C++: Passing a non moveable functor to a std::function
如何將不可移動的對象傳遞給std :: function? 一個簡單的替代方法是傳遞一個std::reference_wrapper
,這將導致功能生命周期的需求取決於對象。 下面的示例代碼可以更好地解釋該問題。
class Player {
std::atomic_int runs {0};
std::string name;
public:
Player(std::string&& name) : name(std::move(name)) {} //...
void inc() { ++runs;}
};
class PlayerStats {
std::array<std::unique_ptr<Player>,2> players;
public:
PlayerStats() {
for(int i = 0; i<2 ; i++)
players[i] = std::unique_ptr<Player>(new Player{"player"+std::to_string(i)});
}
Player* const operator() (int index) const {
return players[index].get();
}
};
using player_total_f = std::function<Player* const(int index)>;
class GameStats {
std::string game;
std::string date;
player_total_f f;
public:
GameStats(std::string&& game, std::string&& date, player_total_f&& _f) :
game(std::move(game)), date(std::move(date)), f(std::move(_f)) {}
};
int main(int argc, char *argv[])
{
PlayerStats st;
//GameStats("game1","10.11",std::ref(st)); //this seems like the only possibility, no way to make GameStats own the functor
return 0;
}
鑒於該函數不可復制,我該如何在此處將PlayerStats
設置為PlayerStats
,似乎唯一可能是std :: ref?
template<class F>
auto shared_function( F&& f ){
auto spf=std::make_shared<std::decay_f<F>>(std::forward<F>(f));
return [spf=std::move(spf)](auto&&...args)->decltype(auto){
return (*pf)(decltype(args)(args)...);
};
}
在共享的ptr中擁有它。 稍微更改語義,但對其進行修復。
或編寫自己的非復制std函數。
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