c++std-functionc++-loki

std::function and shared_ptr


I have been using Loki's Functor for a while and I recently asked a question about it (still unanswered...) I have been told to use std::function, but I prefer Loki's implementation of Functor since it also work with all sorts of pointers as parameters (e.g. std::shared_ptr).

struct Toto
{
    void foo( int param )
    {
        std::cout << "foo: " << param << std::endl;
    }
};

int
main( int argc, const char** argv )
{
    std::shared_ptr<Toto> ptr = std::make_shared<Toto>();

    Loki::Functor<void, LOKI_TYPELIST_1(int)> func( ptr, &Toto::foo );

    func(1);
}

Is there a way to do so with std::function ?


Solution

  • Use std::bind.

    auto func = std::bind(&Toto::foo, ptr, std::placeholders::_1);
    

    here, func will be deduced to type, that was returned from std::bind or if you don't like auto you can use (and you want to use std::function)

    std::function<void(int)> func = std::bind(&Toto::foo, 
    ptr, std::placeholders::_1);
    

    Here std::function will be constructed from result of std::bind. ptr will be copied to some object returned from std::bind, however you can use std::ref/std::cref if you don't want copies.