Lifecycles Reference

Part of the flexibility and extensibility of SnowFox comes from Lifecycles. Lifecycles are a way to react to internal system events and decouple handing of actions. The component system also relies on Lifecycles to dynamically inject features and alternative implementations.

Lifecycles revolve around the sf::core::interface::Lifecycle class, which behaves in a similar manner to Node.js event emitter.

All events are registered and triggered on the same Lifecycle singleton instance throughout the system. Name spaces in the event name are used to avoid conflicts with context.

Lifecycle API

Interactions with the Lifecycles system can be divided into two:

• Event handling: the side that reacts to changes in the system.
• Event triggering: the side that informs lifecycles of a change.

Checkout the Lifecycle interface in the source code at https://github.com/ArcticNature/core/blob/master/interface/lifecycle/include/core/interface/lifecycle.h

Example: acting at process initialisation

//! Example of Lifecycle event handler.
class ExampeInitHandler : public BaseLifecycleHandler {
 public:
  void handle(std::string event, BaseLifecycleArg*) {
    // Some code that needs to run when the process starts.
  }
};
LifecycleStaticOn("process::init", ExampeInitHandler);

int main() {
  // Some init logic ...

  // Trigger the `process::init` event.
  Lifecycle::trigger("process::init");
}

List of official Lifecycles

Events are nothing more then strings that identify a list of handlers. Lifecycles are a sequence of these events triggered by the system. There is no formal checking or definition of lifecycles.

While the system (and components in it) can create their own lifecycles, this section of the reference pages describes the lifecycles part of the core components of SnowFox.