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Date: Thu, 25 Jan 2018 14:48:19 -0600
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To: Niklas Keller <me@kelunik.com>
Cc: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV][RFC][DISCUSSION] Collection Inspection
From: tendoaki@gmail.com (Michael Morris)

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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>

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.

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.

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