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Date: Thu, 25 Jan 2018 22:04:30 +0100
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To: Michael Morris <tendoaki@gmail.com>
Cc: PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="94eb2c146be2418ba50563a02027"
Subject: Re: [PHP-DEV][RFC][DISCUSSION] Collection Inspection
From: me@kelunik.com (Niklas Keller)

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>
> On Thu, Jan 25, 2018 at 2:39 PM, Niklas Keller <me@kelunik.com> wrote:
>
>>
>> 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.
>>
>
> Consistency with instanceof.
>
>
>
> Hmm, it might be possible to just pile this all onto instanceof -
> following Derrick's mention of how Java does things, so here's a third
> implementation approach.  It would look like this:
>
> $a instanceof array<string>
>

That might work, but array<string> should only return true if it's an
array, not for anything that implements ArrayAccess.


> Returns true if $a is an array (or implements array access) and that all
> it's members are strings.
>
> $b instanceof SomeClass<string>
>
> Returns true if SomeClass can be iterated and contains only strings.
>

This would block generics with that syntax then.


> The question is can the token parser handle that pattern?  Or does the
> current usage of < and > in their boolean form block this?
>
> If this third approach is accepted then we have no BC breaks at all since
> there's no new keyword or function. We just have a *very* expanded
> instanceof operator.
>

Regards, Niklas

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