Michael Morris <tendo...@gmail.com> schrieb am Do., 25. Jan. 2018, 21:19:
> On Thu, Jan 25, 2018 at 2:10 PM, Rowan Collins <rowan.coll...@gmail.com> > wrote: > > > On 25/01/2018 14:52, Derick Rethans wrote: > > > >> IMO, it makes a lot more sense to check integrity when creating the > >> "array" structure. Instead, I would suggest to add a native Collection > >> type, that takes a "type" as argument. They aren't quite full generics, > >> but it does 1. fix something; 2. isn't really complicated. > >> > >> What I am suggesting is to add a new syntax "Collection<$type>", > >> mimicking a class, but having a type as "argument": > >> > >> $a = new Collection<integer>; > >> > > > > So would I be right in thinking this would mean adding basic support for > > generics to the engine, but not letting new ones be defined in userland? > > So, a bit like how internal or extension classes have the ability to do > > more overloading of casts and operators than userland classes? > > > > If so, I like the concept, but wonder whether the parts of the > > implementation it would need are the easy parts of the hard ones. I guess > > not being able to inherit from the generic would get rid of a bunch of > > complexity, but don't really know where else the challenge lies. > > > > He's getting the syntax from Java. Java collections allow you to specify > the type they are constrained to in <> after the class name. Type Script > does something similar. The problem is that Java already has the policing > mechanics present in the runtime to police insertions into the collection > and guarantee they are of the correct type. PHP has no such mechanism in > place and in previous discussion threads the primary maintainers have > underscored that adding such is highly difficult. > > It is also completely tangential to and a distraction from what I propose > and would like to focus on here. Regardless of whether PHP ever gets a > core class or construct for type uniform collections, the ability to verify > that variables are a "collection of something" will remain. That is the > issue I want to discuss and address here - verifying that existing > variables are a given collection type, not debating pie-in-the-sky, may > never be implementable classes that self insure their own integrity. > > So, given `$a collectionof string` the operator returns whether or not $a > is, at that time, a collection of strings (be it an array or other > iterable). It doesn't insure $a will stay that way - it's just a check of > the variables status at a given moment, which is the best that can be hoped > for in PHP. > That should be a function, not an operator, unless you can bring up very good arguments to make it an operator. Regards, Niklas >
