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CC: PHP internals <internals@lists.php.net>, Phil Sturgeon
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Date: Wed, 25 May 2016 11:36:52 +0300
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Subject: Re: [PHP-DEV] [RFC][Vote] Typed Properties
From: dmitry@zend.com (Dmitry Stogov)

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On 05/25/2016 11:30 AM, Joe Watkins wrote:
> Morning Dmitry,
>
>    > I made this check(s) to be invariant. You may like to do this 
> differently...
>
>    I think this is what everyone expects, isn't it ?
>
>    I did omit to mention that part ...
>
>    > RFC doesn't define how uninitialized nullable typed properties 
> should behave.
>
>   It does:
>
>    > *Nullable typed properties will not raise an exception when 
> accessed before initialization.*
>
>   It's the only bold text in the document :)
>
>   It seems correct to me; We raise uninitialized exceptions to 
> prohibit the return of null to user land, for nullable properties we 
> don't need to do that.
>
>   It does mean that ?int $foo; has an implicit default value of null, 
> but I can't see anything wrong with that, for a nullable property.

OK. This is the same that I like. I'll change implementation accordingly.
But what should unset() do?
Currently it makes property uninitialized and then it can't accessed.
I suppose it should emit notice and return NULL.
I'll change this as well (in an hour).

Thanks. Dmitry.
>
>   I'm open to being persuaded that is wrong.
>
>   I will review comments and current patch this morning ...
>
> Cheers
> Joe
>
> On Wed, May 25, 2016 at 8:06 AM, Dmitry Stogov <dmitry@zend.com 
> <mailto:dmitry@zend.com>> wrote:
>
>
>
>     On 05/25/2016 09:06 AM, Joe Watkins wrote:
>>     Morning Dmitry,
>>
>>        There's no section for nullables, but there is mention of
>>     them, specifically in relation to your query:
>>
>>        > While parameters allow null to be accepted as the default
>>     value, null is only a valid value for nullable properties.
>>
>>        Is there something wrong with that rule ?
>
>     It's OK. This just should be defined and it's defined in RFC (I
>     missed)
>>
>>        Having explicit nullability means the declaration tells you
>>     all you need to know, all the time.
>>
>>        Being able to set null any typed property means you can never
>>     be sure of the type; You can't tell by looking at the declaration
>>     what type the variable will be because anything is allowed to set
>>     it null.
>>
>>        We waited for explicit nullability to avoid this.
>>
>>        You'll have to have a really good reason for me to change that
>>     rule :)
>>
>>        > Inheritance rules for typed nullable properties are also missed.
>>
>>        That's true, but shouldn't they use the same rules as nullable
>>     parameters, will discussion change how they should work ?
>     I made this check(s) to be invariant. You may like to do this
>     differently...
>     It's  better to define this in RFC, check implementation and add
>     tests.
>
>>
>>        > but still have unsolved problems.
>>
>>        If you have discussed these somewhere, can you send/show the
>>     transcript ? (I missed all comms after yesterday morning, due to
>>     illness).
>
>     We are working with Bob, trying to improve the patch. I added new
>     tests fixing the problems, and also added few comments o github.
>>
>>        If it emerges that the RFC needs to be modified heavily, then
>>     I'm happy to stop the voting.
>
>     RFC doesn't define how uninitialized nullable typed properties
>     should behave.
>
>     class C {
>       public $a;
>       public int $b;
>       public ?int $c;
>     }
>     $obj = new C;
>     var_dump($obj->a); // NULL
>     var_dump($obj->b); // throw Error("")
>     var_dump($obj->c); // first or second??? (currently throw Error("")).
>     $obj->$a = null;
>     $obj->$b = null; // throw Error("")
>     $obj->$c = null;
>     var_dump($obj->a); // NULL
>     var_dump($obj->b); // throw Error("")
>     var_dump($obj->c); // NULL
>     unset($obj->$a);
>     unset($obj->$b);
>     unset($obj->$c);
>     var_dump($obj->a); // notice + NULL
>     var_dump($obj->b); // throw Error("")
>     var_dump($obj->c); // first or second??? (currently throw Error("")).
>
>     This should be defined.
>
>>
>>
>>        But, so far, we haven't actually deviated from the RFC, only
>>     changed implementation details that are not part of the design of
>>     the feature.
>
>     I'm not so sure.
>     Anyway, I hope you are better and we will able to speak today or
>     tomorrow.
>
>     Thanks. Dmitry.
>
>
>>
>>        Sorry if it seems like I'm missing information, I don't know
>>     what you and Bob found out yet ...
>>
>>        I super appreciate you guys working on it, obviously. Thanks
>>     for that :)
>>
>>     Cheers
>>     Joe
>>
>>     On Tue, May 24, 2016 at 8:04 PM, Dmitry Stogov <dmitry@zend.com
>>     <mailto:dmitry@zend.com>> wrote:
>>
>>         Hi Joe,
>>
>>         I've add implementation for nullable typed properties (as
>>         they fit into the patch design), but RFC missed any
>>         description of nullable properties.
>>         See tests
>>         Zend/tests/type_declarations/typed_properties_047.phpt,
>>         Zend/tests/type_declarations/typed_properties_048.phpt,
>>         Zend/tests/type_declarations/typed_properties_049.phpt
>>
>>         I'm not sure, if this is what the voters expect. At least I
>>         don't like the facts that "?int $foo;" declares uninitialized
>>         property; "?int $foo = NULL" may be unset() and became
>>         uninitialized; and it's an open question if "int $foo =
>>         NULL;" should be supported as nullable. Inheritance rules for
>>         typed nullable properties are also missed.
>>
>>         Personally, I think the RFC was moved into voting state too
>>         early (without good enough implementation, and with missing 
>>         topics).
>>         The current implementation is better (performance penalty
>>         reduced to ~2%), but still have unsolved problems.
>>
>>         May be it's better to cancel voting, solve problems, finish
>>         the implementation and add missing questions into RFC...
>>         I'm going to help with implementation in any case, but we
>>         should agree on what we are doing.
>>
>>         Thanks. Dmitry.
>>
>>         ________________________________________
>>         From: Joe Watkins <pthreads@pthreads.org
>>         <mailto:pthreads@pthreads.org>>
>>         Sent: Friday, May 20, 2016 9:05:34 AM
>>         To: PHP internals; Phil Sturgeon
>>         Subject: [PHP-DEV] [RFC][Vote] Typed Properties
>>
>>         Morning internals,
>>
>>             Since we have our answer on nullable types, typed
>>         properties can now go
>>         to vote.
>>
>>         https://wiki.php.net/rfc/typed-properties#vote
>>
>>             Note that, support for nullability as RFC'd will be
>>         merged when the
>>         implementation for nullable_types is merged into master.
>>
>>             Please participate.
>>
>>         Cheers
>>         Joe
>>
>>
>
>


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