Function returning a lambda expression

Question

I wonder if it's possible to write a function that returns a lambda function in C++11. Of course one problem is how to declare such function. Each lambda has a type, but that type is not expressible in C++. I don't think this would work:

auto retFun() -> decltype ([](int x) -> int) {     return [](int x) { return x; } } 

Nor this:

int(int) retFun(); 

I'm not aware of any automatic conversions from lambdas to, say, pointers to functions, or some such. Is the only solution handcrafting a function object and returning it?

Answer 1

You don't need a handcrafted function object, just use std::function, to which lambda functions are convertible:

This example returns the integer identity function:

std::function<int (int)> retFun() {     return [](int x) { return x; }; }