已知类型的C ++可变函数模板 [英] C++ Variadic Function Templates of Known Type

问题描述

我目前正在尝试了解可变参数模板支持可以做的一些事情。假设我有这样的功能-

I'm currently trying to get my head around some of the things I can do with variadic template support. Let's say I have a function like this -

template <typename ... Args>
void foo(Args ... a)
{
    int len = sizeof...(tail);
    int vals[] = {a...};
    /* Rest of function */
}

/* Elsewhere */
foo(1, 2, 3, 4);

此代码有效，因为我事先假设参数将是整数，但如果我提供，显然会失败其他的东西。如果我知道参数包会预先包含特定类型，是否有某种方法可以使我无需模板，并且具有-

This code works because I assume beforehand that the arguments will be integers, but obviously will fail if I provide something else. If I know that the parameter packs will contain a particular type in advance, is there some way that I can do without the templating and have something like -

void foo(int ... a)

我尝试这样做，但是编译器给出了有关foo为空字段的错误。我知道我也可以通过递归访问包中的参数，但是我不确定这是否可以解决我遇到的问题-也就是说，我希望能够采用可变数量的相同类型的参数。

I have tried doing this, but the compiler gave an error about foo being a void field. I know that I can also access the parameters in the pack through recursion, but I'm not sure this will fix the problem that I have - namely I want to be able to take a variable number of arguments of the same type.

推荐答案

这应该有效：

void foo(int);

template<typename ...Args>
void foo(int first, Args... more)
{
   foo(first);
   foo(std::forward(more)...);
}

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