std::async 与重载函数 [英] std::async with overloaded functions

问题描述

可能的重复:

std::bind 重载解析

考虑以下 C++ 示例

Consider following C++ example

class A
{
public:
    int foo(int a, int b);
    int foo(int a, double b);
};

int main()
{
    A a;
    auto f = std::async(std::launch::async, &A::foo, &a, 2, 3.5);
}

这给出了 'std::async' :无法推断模板参数，因为函数参数不明确.我该如何解决这种歧义??

This gives 'std::async' : cannot deduce template argument as function argument is ambiguous. How do I resolve this ambiguity??

推荐答案

帮助编译器解决歧义，告诉您需要哪种重载:

Help the compiler resolve ambiguity telling which overload you want:

std::async(std::launch::async, static_cast<int(A::*)(int,double)>(&A::foo), &a, 2, 3.5);
//                             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^

或改用 lambda 表达式:

or use lambda expression instead:

std::async(std::launch::async, [&a] { return a.foo(2, 3.5); });

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