尝试将lambda传递给构造函数:
#include <functional>
#include <exception>
template<typename R>
class Nisse
{
private:
Nisse(Nisse const&) = delete;
Nisse(Nisse&&) = delete;
Nisse& operator=(Nisse const&) = delete;
Nisse& operator=(Nisse&&) = delete;
public:
Nisse(std::function<R> const& func) {}
};
int main()
{
Nisse<int> nisse([](){return 5;});
}
当我编译时,我收到一条错误消息:
Test.cpp: In function ‘int main()’:
Test.cpp:19:39: error: no matching function for call to ‘Nisse<int>::Nisse(main()::<lambda()>)’
Test.cpp:19:39: note: candidate is:
Test.cpp:14:9: note: Nisse<R>::Nisse(const std::function<R>&) [with R = int]
Test.cpp:14:9: note: no known conversion for argument 1 from ‘main()::<lambda()>’ to ‘const std::function<int>&’
答案 0 :(得分:5)
std::function
模板arg的类型错误。尝试使用
Nisse(std::function<R()> const& func) {}
具体来说,模板参数需要是一个函数类型,但是你传递的只是所需的返回类型。