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Date: Sat, 5 Sep 2015 13:48:51 -0600
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To: =?UTF-8?Q?Pavel_Kou=C5=99il?= <pajousek@gmail.com>
Cc: "Ben Scholzen 'DASPRiD'" <mail@dasprids.de>, PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Generic classes and methods RFC
From: john.lesueur@gmail.com (John LeSueur)

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On Tue, Sep 1, 2015 at 2:54 AM, Pavel Kou=C5=99il <pajousek@gmail.com> wrot=
e:

> On Mon, Aug 31, 2015 at 10:31 PM, Ben Scholzen 'DASPRiD'
> <mail@dasprids.de> wrote:
> > Hello,
> >
> > I've written up an RFC for supporting generic classes and methods in PH=
P,
> > and I'd love to hear your thoughts about it.
> >
> > https://wiki.php.net/rfc/generics
> >
> > Cheers,
> > --
> > Ben Scholzen 'DASPRiD'
> > Community Review Team Member | mail@dasprids.de
> > Zend Framework               | http://www.dasprids.de
> >
> > --
> > PHP Internals - PHP Runtime Development Mailing List
> > To unsubscribe, visit: http://www.php.net/unsub.php
> >
>
> Hello,
>
> I would love to see generics in PHP, but I have a few questions for your
> RFC.
>
> class Bazz<Foo : \Bar>
>
> Why did you use this syntax for forcing extending/implementation? I
> know this is the syntax C# uses, but it doesn't fit PHP. I think it
> should be "extends" or "implements", because in PHP : has a different
> meaning.
>
> Also, how do you specify multiple constraints?
>
> Do you have any idea how it would work internally and if there was
> some performance hit while using generics, and if it would also slow
> down existing apps that don't use generics?
>
> I hope this RFC will have positive comments, and someone who is
> capable of writing C will help you out with it so there's a patch for
> people to review - because I'm not sure if this RFC can get anywhere
> without a patch. :(
>
> Regards
> Pavel Kouril
>
> --
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: http://www.php.net/unsub.php
>
>
Hi Ben,

Now that I have substantive questions, including the list :)

In the following:

class SomeList<Bar> {
    public static function fromArray<Baz>(array $a): SomeList<Baz> {
        $list =3D new SomeList<Baz>();
        $list2 =3D new SomeList<Bar>();
        return $list;
    }
}

$list =3D SomeList<int>::fromArray([1, 2]);

When fromArray() executes, what type is $list2? or is that an error? If
it's an error, what advantage is there to having distinct generic types on
the class vs. the method? How do I specify the two generic types I want to
use?

Another thing I'd like to make sure I understand, how does this interact
with strict types (and non-strict)?

new Entry<int, string>(1, 2);//I assume it should type-juggle

declare(strict_types =3D 1);
new Entry<int, string>(1, 2);//I assume it should throw error

I'm interested to see if PHP can get generics going. I hope hashing out
some more details might garner more interest.


Thanks,
John

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