PHP Event based Inheritance Model: Register handlers to process events in a chain

This package can register handlers to process events in a chain.

It allows the applications to register callback functions that will be called when an event with a given name is triggered.

Multiple callback functions may be registered for the same event.

When an event is triggered, the package will call the last callback function registered to handle that event.

The event handler function that was called may call other callback functions that were registered before to handle the same event.