PSR-14

PSR-14: Example - plugin registration

In Content Management Systems and similar highly-configurable applications, a common pattern is to have a registration mechanism of some sort. That is, some part of the system asks other parts of the system "give me a list of your Things!", and then modules/extensions/plugins (whatever the system calls them) can incrementally build up that list of Things, which the caller then does something with. Those Things can be defined by the extension, or they can be defined by user-configuration and turned into a Thing definition by the module. Both are valid and useful, and can be mixed and matched.

This pattern lends itself very well to an Event system like PSR-14, and in fact the "give me a list of Things" pattern was one of the explicit use cases the Working Group considered. Today let's look at how one could easily implement such a mechanism.

Continue reading this post on SteemIt.

Larry 17 April 2019 - 6:08pm
PSR-14: Example - Access voting

So far in our 5 part series we've dug into the details of Events, Dispatchers, and Providers. An awful lot of flexibility can be had from just three simple methods. But how does it work out in practice?

In today's installment I want to start showing examples of real-world (ish) use cases that can benefit from this design. For these examples I will be using Tukio, my stand-alone PSR-14 implementation, but all will work just as well with any PSR-14 implementation, by design.

Voting based access control

A common "extension point" in many systems is access control, especially in a configurable CMS. You want to limit access to various operations, but which users should have access to what operations could vary based on a wide variety of special-case conditions that you want to allow individual site owners to control.

Continue reading this post on Steemit.

Larry 11 April 2019 - 5:31pm
PSR-14: Compound Providers

In part 3 of this series we looked at the more common patterns of Providers that may be used with a PSR-14 Event Dispatcher. In part 4 we looked at some more complex cases of Providers. Today, we'll bring them all together: Literally.

Recall that a Provider is responsible only for receiving an Event and returning a list of callables that it believes should be invoked on it, in the order it decides (if it cares). How it does that is up to the implementation. In fact, it's not even required to do so itself at all. A Provider can defer that decision to another Provider if it wishes, or, critically, to multiple Providers.

Continue reading this post on SteemIt.

Larry 3 April 2019 - 10:45am
PSR-14: Advanced Providers

In part 3 of our series we looked at some common Provider patterns for PSR-14. But the flexibility and complexity of Providers is limited only by your imagination. Today we'll look at a few more interesting examples of Providers that are all equally valid but tailored to particular use cases.

Continue reading this post on SteemIt.

Larry 1 April 2019 - 11:34am
PSR-14: Being a good Provider

As mentioned back in part 1, PSR-14 splits the core mediator into two objects: The Dispatcher and the Provider. The Dispatcher is fairly straightforward and most implementations will be fairly simple and fairly similar.

Providers are the exact opposite; A Listener Provider has one requirement: It maps the Event object into an iterable of callables, in the order it chooses. How it does that is left up to the Provider to define, and there are dozens of possible ways.

Continue reading this post on SteemIt.

Larry 30 March 2019 - 11:00am
PSR-14: All about Events

In the last installment we discussed the overall structure of PSR-14. Today I'd like to dive into the key aspect of any event system: The Events themselves.

Various different event systems structure events in different ways. Some require that it be an object. Others it's any arbitrary value. Others it's any number of arbitrary values, depending on the Event. Some really really want pass-by-reference arrays.

For PSR-14, we chose to standardize on an object and always an object. There were three main reasons for that:

Continue reading this post on SteemIt.

Larry 28 March 2019 - 11:03am
PSR-14: A Major Event in PHP

The PHP Framework Interoperability Group has released a number of new specifications in the last year. The latest, PSR-14, covers Event Dispatching. Like many PSRs it's a fairly small spec, at the end of the day, but intended to be high-impact.

In this series of posts I want to cover what PSR-14 is and does (and what it isn't and doesn't), and how to best leverage it in your projects as it gets deployed more widely.

Continue reading this post on SteemIt.

Larry 26 March 2019 - 10:44am