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Event System

Uvicore ships with an elegant observer (pub/sub) implementation that lets you listen to things that happen inside the framework, inside the packages you depend on, and inside your own code. When something noteworthy occurs you dispatch an event, and every listener that registered interest in it springs into action.

Events are one of the best tools you have for keeping a project loosely coupled. A single event can have many listeners that know nothing about each other. When a wiki post is created, for example, one listener might email the watchers, another might post to Slack, and a third might warm a cache, all without the code that created the post knowing any of them exist.

This is the O in S.O.L.I.D in action, code that is open for extension but closed for modification. By firing events at the interesting moments in your code, you let other developers (and your future self) hook in new behavior without ever touching the original. It is a kindness worth doing early, so sprinkle events throughout your packages from the start.

What's Inside

  • Defining Events - Create strict, discoverable class events or quick string events.
  • Dispatching Events - Fire your events synchronously or asynchronously.
  • Listening to Events - Subscribe handlers, with priorities, wildcards and bulk subscriptions.
  • Handling Events - Write the callbacks, functions, classes and subscriptions that do the work.
  • Built-in Events - The lifecycle, HTTP, console and ORM events Uvicore fires for you.

Highlights

  • Sync and async - Events are flagged synchronous or asynchronous and dispatched accordingly.
  • Priorities - Order your listeners with a simple priority (default 50, lower runs first).
  • Wildcards - Listen to whole families of events like uvicore.foundation.events.*.
  • Subscriptions - Group many listeners and their handlers into a single tidy class.

Tip

Class based events register themselves into the IoC Container, so you can discover everything that is listenable at any time with ./uvicore event list. See Built-in Events for the full set of inspection commands.