lambda-worker.cpp

#include <functional>
#include <iostream>
#include <vector>

int sum(int a, int b) { return a + b; }

int sub(int a, int b) { return a - b; }

struct multiply {
  int operator()(int a, int b) { return a * b; }
};

struct divide {
  int operator()(int a, int b) { return a / b; }
};

struct worker {
  // Polymorphic function type
  using element = std::function<int(int)>;
  std::vector<element> queue_;

  template <typename T> void queue(T&& callable) {
    queue_.push_back(std::forward<T>(callable));
  }

  int go(int initial) {
    int value = initial;

    for (auto &item : queue_) {
      value = item(value);
    }
    return value;
  }
};

int main() {
  worker my_worker;

  // queue the work here
  my_worker.queue([](int i) { return sum(i, 5); });  // sum  5
  my_worker.queue([](int i) { return sub(i, 15); }); // sub  15
  my_worker.queue([](int i) { return divide{}(i, 3); });      // div  3
  my_worker.queue([](int i) { return sub(i, 10); }); // sub  10
  my_worker.queue([](int i) { return multiply{}(i, 4); });      // mult 4

  int result = my_worker.go(100);
  std::cout << "result: " << result << std::endl;

  return 1;
}