将可变参数列表插入向量？ [英] Inserting a variadic argument list into a vector?

问题描述

原谅我，如果这已经回答了，因为我找不到它...

Forgive me if this has been answered already, as I couldn't find it...

基本上我有一个对象，需要一个可变参数列表在它的构造函数中，并将参数存储在向量中。如何从可变参数构造函数的参数初始化一个向量？

Basically I have an object that needs to take a variadic argument list in it's constructor and store the arguments in a vector. How do I initialize a vector from a the arguments of a variadic constructor?

class GenericNode {
public:
    GenericNode(GenericNode*... inputs) {
            /* Something like... */
        // inputs_.push_back(inputs)...;
}
private:
    std::vector<GenericNode*> inputs_;
};

推荐答案

是使用初始化程序列表

#include <initializer_list>
#include <vector>
class GenericNode {
public:
    GenericNode(std::initializer_list<GenericNode*> inputs) 
        :inputs_(inputs) {} //well that's easy
private:
    std::vector<GenericNode*> inputs_;
};
int main() {
    GenericNode* ptr;
    GenericNode node{ptr, ptr, ptr, ptr};
} //compilation at http://stacked-crooked.com/view?id=88ebac6a4490915fc4bc608765ba2b6c

使用C ++ 11最接近你已经有的东西是使用向量的initializer_list：

The closest to what you already have, using C++11 is to use the vector's initializer_list:

    template<class ...Ts>
    GenericNode(Ts... inputs) 
        :inputs_{inputs...} {} //well that's easy too
    //compilation at http://stacked-crooked.com/view?id=2f7514b33401c51d33677bbff358f8ae

下面是一个没有initializer_lists的C ++ 11版本。它是丑陋，复杂，需要许多编译器缺少的功能。使用初始值列表

And here's a C++11 version with no initializer_lists at all. It's ugly, and complicated, and requires features missing from many compilers. Use the initializer list

template<class T>
using Alias = T;

class GenericNode {
public:
    template<class ...Ts>
    GenericNode(Ts... inputs) { //SFINAE might be appropriate
         using ptr = GenericNode*;
         Alias<char[]>{( //first part of magic unpacker
             inputs_.push_back(ptr(inputs))
             ,'0')...,'0'}; //second part of magic unpacker
    }
private:
    std::vector<GenericNode*> inputs_;
};
int main() {
    GenericNode* ptr;
    GenericNode node(ptr, ptr, ptr, ptr);
} //compilation at http://stacked-crooked.com/view?id=57c533692166fb222adf5f837891e1f9
//thanks to R. Martinho Fernandes for helping me get it to compile

与一切无关，我不知道这些是否拥有指针。如果是，请改用 std :: unique_ptr 。

Unrelated to everything, I don't know if those are owning pointers or not. If they are, use std::unique_ptr instead.

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