[英]omit std::placeholders in std::bind
To create std::function, here is what I do:- 要创建std :: function,我就是这样做的: -
std::function<void(int,int,int)> f=
std::bind(&B::fb,this,
std::placeholders::_1,
std::placeholders::_2,
std::placeholders::_3
);
void B::fb(int x,int k,int j){} //example
It is obvious that B::fb
receive three parameters. 很明显,
B::fb
接收三个参数。
To increase readability & maintainablity, I wish I could call this instead :- 为了提高可读性和可维护性,我希望我可以这样称呼: -
std::function<void(int,int,int)> f=std::bind(&B::fb,this); //omit _1 _2 _3
Question 题
Are there any features in C++ that enable omitting the placeholders? C ++中是否有任何功能可以省略占位符?
It should call _1,_2, ..., in orders automatically. 它应该自动在命令中调用_1,_2,....
I have googled "omit placeholders c++" but not find any clue. 我用谷歌搜索“省略占位符c ++”但没有发现任何线索。
You may create functions helper (those ones are C++14): 您可以创建函数帮助程序(那些是C ++ 14):
template <class C, typename Ret, typename ... Ts>
std::function<Ret(Ts...)> bind_this(C* c, Ret (C::*m)(Ts...))
{
return [=](auto&&... args) { return (c->*m)(std::forward<decltype(args)>(args)...); };
}
template <class C, typename Ret, typename ... Ts>
std::function<Ret(Ts...)> bind_this(const C* c, Ret (C::*m)(Ts...) const)
{
return [=](auto&&... args) { return (c->*m)(std::forward<decltype(args)>(args)...); };
}
and then just write 然后写
std::function<void(int, int, int)> f = bind_this(this, &B::fb);
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