Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:92039
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain zend.com designates 157.56.111.115 as permitted sender)
To: Joe Watkins <pthreads@pthreads.org>, =?UTF-8?Q?Bj=c3=b6rn_Larsson?=
	<bjorn.x.larsson@telia.com>
References: <CABDNdAHwgx+LJRc_gi9citiypxxWVGFMB+6hrmU+vVYDWCDV_g@mail.gmail.com>
 <3F.70.02405.6803BE65@pb1.pair.com> <56F01545.8080008@gmail.com>
 <CAF+90c-Z82kBT18ivvKejD5_dBf=dtbNYN-cZcyO1K=0C1WcLA@mail.gmail.com>
 <56F14572.701@gmail.com> <56F15EF5.80006@telia.com>
 <56F16023.1010002@gmail.com>
 <CAPhkiZxYwXKLp8ASkjiwXgzDtjKxJ8rYROCM-t=8sU5=efhg2w@mail.gmail.com>
 <CAPhkiZwOJOkNu4N=h+wQRX4w8-KV=zg9x4khhLRLu199YcqZxw@mail.gmail.com>
 <CABDNdAGh4OjkkEQim6oYK=sZ=zj1Q==HzE=SLJ1E8=a=ku1DqA@mail.gmail.com>
 <CY1PR0201MB17863E4B9D9F53151A900DCDBF870@CY1PR0201MB1786.namprd02.prod.outlook.com>
 <CAL=_i_mNwmpg0PWmrm3nTZxn6s33u2QUzavk8w0Fk1OGvbWJtA@mail.gmail.com>
 <CY1PR0201MB1786AAFDC6170AB1585CA7F5BF870@CY1PR0201MB1786.namprd02.prod.outlook.com>
 <CY1PR0201MB17867DAC10D401EE9EC49CBCBF870@CY1PR0201MB1786.namprd02.prod.outlook.com>
 <CAL=_i_knwzrcXdx1k4ii8YKzrgaREBFcHYGC9ZV_J05ZWVWmzg@mail.gmail.com>
 <56FC4ED6.6050701@telia.com>
 <CAL=_i_ksOzCV1SUtB2jwSYPm1SL2y3jy43+JSZ3k6KRywsizUg@mail.gmail.com>
CC: Phil Sturgeon <pjsturgeon@gmail.com>, Krakjo <krakjoe@php.net>, PHP
 internals <internals@lists.php.net>
Message-ID: <56FCE6C9.1050302@zend.com>
Date: Thu, 31 Mar 2016 11:58:49 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.7.1
MIME-Version: 1.0
In-Reply-To: <CAL=_i_ksOzCV1SUtB2jwSYPm1SL2y3jy43+JSZ3k6KRywsizUg@mail.gmail.com>
Content-Type: multipart/alternative;
	boundary="------------070103060202010203010303"
SpamDiagnosticOutput: 1:23
SpamDiagnosticMetadata: NSPM
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 31 Mar 2016 08:59:05.3672 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BLUPR0201MB1778
Subject: Re: [PHP-DEV] [RFC Discussion] Typed Properties
From: dmitry@zend.com (Dmitry Stogov)

--------------070103060202010203010303
Content-Type: text/plain; charset="utf-8"; format=flowed
Content-Transfer-Encoding: 8bit



On 03/31/2016 11:34 AM, Joe Watkins wrote:
> Morning,
>
> > Given that public is implied for all properties above there
> > is a value in having the same rule for type.
>
> public $bar, int $foo;
>
> What does this mean?
>
> If it's not an error, what does this mean ?

This should be a error. I also think, that "public" might be omitted, 
and it should be possible to write "int $bar, $foo".

>
> public $bar, int $foo, $qux;
>
> If it's an error, why is it an error ?
>
> Both of these examples are just as ambiguous as
>
> public int $foo, $bar, $qux;

You say - C, C++, Java, HHVM, etc - all made worse decision? OK...

>
> Access modifiers are assumed to apply to all declarations in a group, 
> because that's what grouping is actually for.
>
> We don't need to make grouping about types, we need to make type 
> declarations unambiguous.

Very strange grouping decision.
At least your opinion is questionable and except for other languages, 
you see a number of opponents on @internals.

Thanks. Dmitry.

>
> > Anyway, in Hack following syntax passes: https://3v4l.org/3tUu9
>
> Hack does not consider types implicitly nullable.
>
> <?hh
> class Foo {
>   public int $int = null;
>   public stdClass $std = null;
> }
>
> things.php:3:10,12: Wrong type hint (Typing[4110])
>   things.php:3:10,12: This is an int
>   things.php:3:21,24: It is incompatible with a nullable type
> things.php:4:10,17: Wrong type hint (Typing[4110])
>   things.php:4:10,17: This is an object of type stdClass
>   things.php:4:26,29: It is incompatible with a nullable type
>
> <?hh
> function foo(int $int = null, stdClass $std = null) {}
>
> things.php:2:18,21: Wrong type hint (Typing[4110])
>   things.php:2:14,16: This is an int
>   things.php:2:25,28: It is incompatible with a nullable type
> things.php:2:40,43: Wrong type hint (Typing[4110])
>   things.php:2:31,38: This is an object of type stdClass
>   things.php:2:47,50: It is incompatible with a nullable type
>
> HHVM doesn't care about types ... we don't compare our type system to 
> that ...
>
> Cheers
> Joe
>
> On Wed, Mar 30, 2016 at 11:10 PM, Björn Larsson 
> <bjorn.x.larsson@telia.com <mailto:bjorn.x.larsson@telia.com>> wrote:
>
>     Den 2016-03-30 kl. 05:16, skrev Joe Watkins:
>
>         Morning Dmitry,
>
>             1) static typed properties are prohibited. why?
>
>         Feels like that's a separate feature, static properties are as
>         good as
>         makes no difference, global variables.
>
>         Instance properties, the engine has good control over their
>         manipulation,
>         for static properties it doesn't, it's not impossible, but
>         feels separate.
>
>     Good that it's clarified in the RFC since one could easily
>     believe that it's possible to set type for a static property.
>
>
>             2) The handling of multiple properties in the same
>             declaration statement
>
>         is inconsistent.
>
>         This feels consistent to me .. in other languages where the
>         type is
>         required, it makes sense to assume the type is implied.
>
>         In a language where the type is optional, public int $foo,
>         $bar; feels
>         ambiguous to me.
>
>     Given that public is implied for all properties above there
>     is a value in having the same rule for type.
>
>
>             3) We already have nullable arguments without any special
>             syntax. We
>
>         should reuse the similar approach for properties.
>
>         Making properties implicitly nullable defeats the object of
>         trying to
>         provide type safety.
>
>         Null is never a valid value for a typed property, if it were,
>         you would
>         never be sure of the type of variable you are getting, and
>         would have to
>         litter your code with is_null checks.
>
>     Maybe good to clarify difference towards default parameters?
>     Anyway, in Hack following syntax passes: https://3v4l.org/3tUu9
>
>
>             I think it might be better to implicitly initialize them
>             according to
>
>         type (if default value is not provided): bool by false, int by
>         0, double by
>         0.0, string by "" (interned), array by [] (immutable), objects
>         by NULL
>         (always nullable).
>
>         Definitely not, lying about the default value isn't a good idea.
>
>         There are times when 0 is as valid as 1, or any other value
>         for an int.
>
>         If you have declared that you know the type of the property,
>         and you write
>         code that accesses that property before there is any possible
>         chance you
>         have set the property, that's a programming error.
>
>         We should not hide that error with a default value, or by
>         allowing the
>         engine to return null.
>
>     Don't have a strong opinion on this one, can see both views.
>     Maybe a bit affected by programming in Java recently, having
>     a slightly more positive attitude towards default values ;-)
>
>     Regards //Björn Larsson
>
>


--------------070103060202010203010303--