Defining Events In Your Classes

libnick events are designed to easily integrate within your classes to easily notify consumers of changes in state of an object.

Let's take a look at Nickvision::Helpers::JsonFileBase and how it defines and uses events.

namespace Nickvision::Helpers
{
  class JsonFileBase
  {
  public:
      ...
      Events::Event<Events::EventArgs>& saved()
      {
          return m_saved;
      }
 
      bool save()
      {
          ...
          saved({}); //Same as saved.invoke({});
          ...
      }
 
  private:
      ...
      Events::Event<Events::EventArgs> m_saved;
  };
}

Here we can see how Nickvision::Helpers::JsonFileBase defines a saved Nickvision::Events::Event, exposes it to the consumer, and triggers/invokes the event within its save method.

A consumer of Nickvision::Helpers::JsonFileBase can easily subscribe to the event, via the subscribe() method or += operator, and have its handler called when the configuration object is saved:

using namespace Nickvision::Events;
using namespace Nickvision::Helpers;
 
void handler(const EventArgs& e)
{
    std::cout << "Config saved." << std::endl;
}
 
int main()
{
    JsonFileBase base{ ... };
    base.saved() += handler;
    base.save();
}

This program will print Config saved. as a result of the event being invoke once the save method was called.