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Date: Wed, 20 Apr 2016 11:17:06 -0400
Message-ID: <CAFp73XtkKr0DELx8DWr-n83sfJrk184fXFmDXiz5CKOAHG6Rew@mail.gmail.com>
To: Rowan Collins <rowan.collins@gmail.com>
Cc: PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a1133bd7862d3bd0530ec1706
Subject: Re: [PHP-DEV] [RFC:generics]
From: guilhermeblanco@gmail.com ("guilhermeblanco@gmail.com")

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Content-Type: text/plain; charset=UTF-8

Sure, the usage of "instanceof" is an alternative to prevent declaring a
new keyword. PHP doesn't have the same problem as Java does to enforce the
first generic type information to be a class and others interfaces. So in
this:

class A {}
interface B {}
interface C {}

class Foo<T instanceof A & B & C> {}

Java required A to be the first due to its compilation process, which PHP
does not have. PHP would accept any order of A, B and C there, like "C & B
&A".


PS: I like to use Java as a base for Generics because I feel it more well
thought than other language implementations (like .NET and Swift).

Regards,

On Wed, Apr 20, 2016 at 11:01 AM, Rowan Collins <rowan.collins@gmail.com>
wrote:

> guilhermeblanco@gmail.com wrote on 20/04/2016 03:54:
>
>> 1- Even though mentioned, I'd still use "extends" or "implements" instead
>> of "is" (which would be a new pseudo-reserved keyword) to enforce data
>> type
>> consistency and prevent developers to potentially referring to one thing
>> while consider another.
>>
>
> Perhaps "instanceof" would make more sense here? "class FileProcessor<T
> extends FileHandle>" seems to exclude instantiating
> FileProcessor<FileHandle>, because "FileHandle extends FileHandle" doesn't
> make any sense.
>
> You could read "class Box<T instanceof Boxable>" as an assertion that the
> class passes the constraint, as in "public function __construct(T $t) {
> assert($t instanceof Boxable); }"
>
> Regards,
> --
> Rowan Collins
> [IMSoP]
>
>
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> PHP Internals - PHP Runtime Development Mailing List
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>


-- 
Guilherme Blanco
Lead Architect at E-Block

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