A thread-safe C++20 Event Library

---

Description

Ereignis is a library that implements an easy to use Event/Callback mechanism that allows for lazy-evaluation of the the results returned by fire.

Installation

Note
This library requires a C++20 capable compiler. In case you need support for C++17 checkout version 1.2

• With FetchContent

  include(FetchContent)
  
  FetchContent_Declare(ereignis GIT_REPOSITORY "https://github.com/Curve/ereignis")
  FetchContent_MakeAvailable(ereignis)
  
  target_link_libraries(<target> ereignis)

• As Git-Submodule

  $ git clone https://github.com/Curve/ereignis

  add_subdirectory(ereignis)
  target_link_libraries(<target> ereignis)

Usage examples

• Basic callback

  #include <ereignis/manager.hpp>
  
  using ereignis::event;
  
  ereignis::manager<
    event<0, void(int)>
  > manager;
  
  manager.at<0>().add([](int i) { std::cout << i << std::endl; });
  manager.at<0>().fire(1337);

• Result iteration

  #include <ereignis/manager.hpp>
  
  enum class window_event
  {
    close
  };
  
  using ereignis::event;
  
  ereignis::manager<
    event<window_event::close, bool()>
  > manager;
  
  manager.at<window_event::close>().add([]() -> bool { return true; });
  
  manager.at<window_event::close>().add([]() -> bool 
  { 
    std::cout << "Reached!" << std::endl; 
    return false; 
  });
  
  // Lets fire all callbacks until we get `true`.
  
  for (const auto& result : manager.at<window_event::close>().fire())
  {
    if (result)
    {
      return;
    }
  }
  
  // 'Reached!' will never be printed.