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Date: Sat, 20 Oct 2012 14:02:00 -0700
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Subject: Re: [PHP-DEV] Generics proposal
From: rasmus@lerdorf.com (Rasmus Lerdorf)

On 10/20/2012 01:59 PM, Nikita wrote:
> Hello, list. I want to propose generics. For those, who don't know what it is, here's example: say we have a Comment class, that has a method getBody. Also we have Collection class, that implements Traversable. Now, if I want to validate all insertions into collection of comments, I would need to create CommentCollection class, extend it from Collection, and override all the methods that are dealing with adding new elements to collection. Moreover, I can't have any hints from my IDE about type of collection's elements, so if I'll have code like this:
> foreach ($commentCollection as $comment) {
>     $comment->getBody();
> }
> There will be no way for IDE to know, of what type that object will be.
> 
> But there's how I could solve my problem with generics:
> class Collection<T> implements Traversable
> {
>     ...
>     public function add(T $element){}
> }
> $collection = new Collection<Comment>();
> 
> $collection->add(new Comment());
> 
> $collection->add("that will be error");
> 
> Actually, that's, again, all about type hinting. If we went so far with scalar type hinting, then generics would also be a good addition.
> 
> So, what you think?

Personally I would hate to see this anywhere near PHP.

-Rasmus