CODEWITHSUNDEEP
c++multithreadingarguments
shashashamti2008
shashashamti2008

Reputation: 2337

Passing any function with any number of arguments to another function

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);
}

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

Upvotes: 0

Views: 168

Answers (1)

Remy Lebeau
Remy Lebeau

Reputation: 598011

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);
}

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();
}

Upvotes: 1

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