Why cannot I use an instantiation of std::make_shared as a pointer to function?
c++, c++11, std, templates
Solution
You just need to be explicit about which constructor you want it to use:
Generator generator(std::make_shared<FromInt, int>);
The "extra" template argument(s) correspond to the constructor arguments.
Problem
When a class has a default constructor, I can use the instantiation of `std::make_shared` in the same way as a pointer to a function. This is probably because the instantiated template has to be compiled and stored in memory and its address must exist. ``` #include <memory> #include <functional> class DefaultConstructible { }; typedef std::function<std::shared_ptr<DefaultConstructible>()> Generator; int main() { Generator generator(std::make_shared<DefaultConstructible>); std::shared_ptr<DefaultConstructible> defConst = generator(); return 0; } ``` But the same thing fails when I add a non-trivial constructor: ``` #include <memory> #include <functional> class FromInt { public: FromInt(int a):a_(a){} int a_; }; typedef std::function<std::shared_ptr<FromInt>(int)> Generator; int main() { Generator generator(std::make_shared<FromInt>); std::shared_ptr<FromInt> p = generator(2); return 0; } ``` I get a compiler error: ``` error: no matching function for call to 'std::function<std::shared_ptr<FromInt>(int)>::function(<unresolved overloaded function type>)' Generator g(std::make_shared<FromInt>); ^ ``` Why is this so and how can I make my code compile?