Using a template function as a template param in another function

Question

I was wondering, how I can do the following in C++?

template <typename T>
T doSomething(T x, T y) {
  T result = /*do something*/;

  return result;
}

template <typename T , typename V> 
T doMore(**input doSomething as template**, V v){
  T result = doSomething<V>(v,0); 
  return result;
}

I am basically trying to use a template function with its template valuetype in another function as such, is there any way to do that?

Answer 1

You cannot pass (the set of) function template as argument (you can pass specific instantiation though).

You might pass functor to solve your issue:

template <typename T>
T doSomething(T x, T y) {
  T result = /*do something*/;

  return result;
}

template <typename F, typename V> 
T doMore(F f, V v){
  T result = f(v, V{0}); 
  return result;
}

And then

doMore([](auto x, auto y){ return doSomething(x, y); }, 42);