#include <string>
#include <iostream>

#include <observe/event.h>

void example() {
  // events can be valueless
  observe::Event<> eventA;

  // or have arguments
  observe::Event<std::string, float> eventB;
  
  // connect will always trigger when an event is triggered
  eventA.connect([](){
    std::cout << "A triggered" << std::endl;
  });
  
  // observers will remove themselves from the event on destroy or reset
  observe::Observer observer = eventB.createObserver([](const std::string &str, float v){ 
    std::cout << "B triggered with " << str << " and " << v << std::endl;
  });

  // call emit to trigger all observers
  eventA.emit();
  eventB.emit("meaning of life", 42);

  // `observe::Observer` can store any type of observer
  // previous observers will be removed
  observer.observe(eventA, [](){ std::cout << "I am now observing A" << std::endl; });

  // to remove an observer without destroying the object, call reset
  observer.reset();
}

observe::Value a = 1;
observe::Value b = 2;

// contains the sum of `a` and `b`
observe::DependentObservableValue sum([](auto a, auto b){ return a+b; },a,b);

// all observable values contain an `Event` `onChange`
sum.onChange.connect([](auto &v){ 
  std::cout << "The result changed to " << r << std::endl;
});

// access the value by dereferencing
std::cout << "The result is " << *sum << std::endl; // -> the result is 3

// changes will automatically propagate through dependent values
a.set(3); // -> The result changed to 5