Hi Michael, I'm at work right now, so I'll just comment on middleware pattern issue.
Yeah, I think shelf is what I was looking at when I picked up the idea. >From the documentation: > A handler is any function that handles a shelf.Request and returns a shelf.Response. It can either handle the request itself--for example, a static file server that looks up the requested URI on the filesystem--or it can do some processing and forward it to another handler--for example, a logger that prints information about requests and responses to the command line. > > The latter kind of handler is called "middleware", since it sits in the middle of the server stack. So I'm not the only who thinks it's fair to call this "middleware". The fact that many other types of handlers would be able to adhere to the same interface signature should be additional huge benefit - a router, for example, could implement that interface directly, making it useful as a handler anywhere, not just as middleware. It's one of the things I like about this pattern - it fits for so many different scenarios, which means these components will potentially useful in so many cases. We'll need that interface under any circumstances - I would be totally fine with terming it a handler rather than middleware interface, because it is incredibly useful, not just for building a middleware stack... On Mon, Apr 24, 2017 at 1:38 PM, Michael Mayer <[email protected]> wrote: > On Friday, April 21, 2017 at 10:12:12 PM UTC+2, Rasmus Schultz wrote: >> >> Hi Michael :-) >> >> > As a handler objects holds a reference to the next handler object, it >> is not reusable anymore. >> >> Well, the instance itself isn't "reusable" - but the code is, that's what >> matters, isn't it? >> > > Not always, I believe the current PSR-15 is superior in a React > <https://github.com/reactphp/react> environment. On first glance: > > 1. less memory usage > 2. better GC > > – but maybe I'm wrong on that. > > >> Callables in PHP are also objects, and a quick benchmark indicates >> literally no difference between a closure and an idempotent functional >> component - the creation overhead is more or less identical: >> >> https://gist.github.com/mindplay-dk/0d4e073179fedb9bb10663c3ffe22336 >> > > At first, you did it wrong :-) – see my gist comment. Secondly, you've > mixed my two arguments, but my main concern was about naming things right, > not about performance. To me Middleware is a pattern of Functional > Programming: > > 1. Middlewares are defined by lambdas/__invoke/… > 2. Middlewares use Continuation-Passing Style (CPS) > <https://en.wikipedia.org/wiki/Continuation-passing_style>: > $next encapsulates the remaining computation > > You know, I like the pattern you are proposing, but calling it Middleware > does not fit to me: it is pure OOP. Calling it Middleware might sound sexy, > but would need intense mental gymnastics to see a FP-Pattern. > > I'm only aware of shelf <https://pub.dartlang.org/packages/shelf> in the > Dart world: > > Middleware can be thought of as a function that takes a handler and wraps >> it in another handler to provide additional functionality. > > > Hence, I'm not sure which Dart framework you are referring to (Btw, that > is the same idea as Pythons Django > <https://docs.djangoproject.com/en/1.11/topics/http/middleware/> Middlewares, > only the names differ). > > Applying this idea to PHP, one probably comes up with these interfaces: > > interface RequestHandler { > function __invoke(ServerRequestInterface $request); > } > > interface Middleware { > function __invoke(RequestHandler $handler) : RequestHandler; > } > > That Middleware interface also solve some __constructor issues, but > obviously come with other disadvantages. > > *tl;tr:* I love that pattern, but calling it Middleware sounds wrong. > > About all your one-to-many successor concerns: I fully agree, and a Router > is a good example which should not be implemented as a Middleware and > moreover should not dispatch Middlewares. The current design I'm using, can > be pictured as: > > > <https://lh3.googleusercontent.com/-aKVlR3yNCRk/WP3g7-1mscI/AAAAAAAAAGw/CRqiwo7l0SEWSN2KQShftL0mljCTsF47QCLcB/s1600/RequestHandlerVsMiddleware.png> > > > IMO, treating everything as Middleware is just as wrong as treating > everything as RequestHandler. I want to use Middlewares to implement > cross-cutting concerns, which justifies that they sit in the middle of the > application stack, e.g. the LogMiddleware in the picture above. However, it > would be strange to create multiple LogMiddleware instances: we have only > one single log file. And it would also be strange, if LogMiddleware has a > successor property, because that way it could only log things of a single > successor. > > Michael > > -- > You received this message because you are subscribed to a topic in the > Google Groups "PHP Framework Interoperability Group" group. > To unsubscribe from this topic, visit https://groups.google.com/d/ > topic/php-fig/B3jtdJA7-6w/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To post to this group, send email to [email protected]. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/php-fig/267f5a3d-2e5a-4db3-b41e-f90cdf149e37%40googlegroups.com > <https://groups.google.com/d/msgid/php-fig/267f5a3d-2e5a-4db3-b41e-f90cdf149e37%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "PHP Framework Interoperability Group" group. 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