将具有任意数量参数的任何函数传递给另一个函数 [英] Passing any function with any number of arguments to another function

问题描述

我正在尝试创建一个C ++函数，该函数接受带有任意数量参数的任何函数，并将其传递给 std :: thread 来启动带有它的线程.

I am trying to create a C++ function that takes any function with any number of arguments and pass it to std::thread to start a thread with it.

#include <iostream>
#include <thread>

#define __PRETTY_FUNCTION__ __FUNCSIG__

void runFunctionInThread(void(*f)()) { std::thread t(f); t.join(); }
void runFunctionInThread(void(*f)(int), int value) { std::thread t(f, value); t.join(); }
void runFunctionInThread(void(*f)(int, int), int value1, int value2) { std::thread t(f, value1, value2); t.join(); }

void isolatedFunc1()                       { std::cout << __PRETTY_FUNCTION__ << "\n"; }
void isolatedFunc2(int value)              { std::cout << __PRETTY_FUNCTION__ << " value is " << value << "\n"; }
void isolatedFunc3(int value1, int value2) { std::cout << __PRETTY_FUNCTION__ << " value1+value2 is " << value1 + value2 << "\n"; }

int main() {

    runFunctionInThread(&isolatedFunc1);
    runFunctionInThread(&isolatedFunc2, 2);
    runFunctionInThread(&isolatedFunc3, 3, 3);
}

是否总有一个单一的 runFunctionInThread 函数可用于具有任意数量的参数和任何类型的任何函数?

Is there anyway to create a single runFunctionInThread function that works for any function with any number of arguments and any type?

推荐答案

使用变量模板及其参数的完美转发，例如:

Use a variadic template with perfect forwarding of its parameters, eg:

#include <iostream>
#include <thread>

#define __PRETTY_FUNCTION__ __FUNCSIG__

template<class Function, class... Args>
void runFunctionInThread(Function f, Args&&... args) {
    std::thread t(f, std::forward<Args>(args)...);
    t.detach();
}
 
void isolatedFunc1()                       { std::cout << __PRETTY_FUNCTION__ << "\n"; }
void isolatedFunc2(int value)              { std::cout << __PRETTY_FUNCTION__ << " value is " << value << "\n"; }
void isolatedFunc3(int value1, int value2) { std::cout << __PRETTY_FUNCTION__ << " value1+value2 is " << value1 + value2 << "\n"; }

int main()
{
    runFunctionInThread(&isolatedFunc1);
    runFunctionInThread(&isolatedFunc2, 2);
    runFunctionInThread(&isolatedFunc3, 3, 3);
}

但是，这是相当多余的，因为 std :: thread 可以直接为您处理此操作，因此您根本不需要 runFunctionInThread()，例如:

However, this is fairly redundant since std::thread can handle this directly for you, so you don't need runFunctionInThread() at all, eg:

int main()
{
    std::thread(&isolatedFunc1).detach();
    std::thread(&isolatedFunc2, 2).detach();
    std::thread(&isolatedFunc3, 3, 3).detach();
}

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