Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:93602
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: error (pb1.pair.com: domain lsces.co.uk from 217.147.176.214 cause and error)
To: internals@lists.php.net
References: <20160525215208.034FC1A801B3@dd1730.kasserver.com>
 <e194be7d-2d72-945c-b8de-245e91f6f239@thefsb.org>
 <CAO3MkaD==1jQvS_cRbDrBQ7nkoBvoAaavmgxeMiP0mSKXL7eRQ@mail.gmail.com>
 <D36C9366.6E7CA%fsb@thefsb.org>
 <5fd54aa0-4fdf-c1e7-eae8-765aa89c8498@fleshgrinder.com>
 <cb4f05df-c5fa-68db-453a-274d42c2c15e@gmail.com>
 <08963b03-8394-6d62-4e5b-393f3fcb5647@fleshgrinder.com>
 <9e9db70d-d72d-d93e-0c81-18c2aa228618@gmail.com>
 <409002d8-b5e3-5990-7358-246adc7e3cab@fleshgrinder.com>
 <57474A08.80807@lsces.co.uk>
 <6f7403b6-bf22-a12b-dfb2-43fe82983e7d@fleshgrinder.com>
 <57474F9C.6080104@lsces.co.uk>
 <1733cfce-001b-1079-e929-88f7dde0f2dd@gmail.com>
 <57475F27.3090306@lsces.co.uk>
 <34edcbd1-2d6a-cd52-7bbb-c393ab62d32d@gmail.com>
 <574772BA.3030305@lsces.co.uk>
 <a6d08adb-198f-4696-3b25-2790480ce1f6@gmail.com>
Message-ID: <5748164C.7020803@lsces.co.uk>
Date: Fri, 27 May 2016 10:41:32 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101
 Thunderbird/38.7.0
MIME-Version: 1.0
In-Reply-To: <a6d08adb-198f-4696-3b25-2790480ce1f6@gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Subject: Re: [PHP-DEV] [RFC][Vote] Typed Properties
From: lester@lsces.co.uk (Lester Caine)

On 27/05/16 09:27, Rowan Collins wrote:
>>>>> // accessing $me->marriage or $me->death returns NULL (because they
>>>>>> allow nulls) but raises E_NOTICE
>>>> BUT DateTime currently will not store 'null' - it returns 'now'
>>>> instead.
>>>> We end up having to store string or integer values because we can't
>>>> store a null date :(
>>>
>>> That's exactly what ?DateTime is for - "either DateTime or Null", just
>>> like in a database.
>>>
>>> In most type systems, there is no such thing as "a null date" - if it's
>>> null, it's not a date, it's a null value.
>>
>> The exact question here then is in relation to just how one uses
>> 'DateTime' in this situation? Or more accurately how one maintains the
>> 'or Null' state when the type does not allow null itself?
> 
> I don't understand the question.
> 
> class Foo { ?DateTime $d }
> $f = new Foo;
> $f->d = null;
> $f->d = new DateTime;
> 
> It's either a DateTime, or it's null.

Now I am confused, but it's probably because I'm looking at a simple

$f->d = new DateTime( $initial );

While you are looking at

If ( isset($initial) )
then $f->d = new DateTime( $initial );
else $f->d = null;

While the original code would have simply been

$f->d = $initial;

And in an ideal world, because $d has been typed as DateTime this would
magically run 'new DateTime($initial)' which is where I am stumbling
because *I* simply look at '?DateTime $d' as creating a DateTime object
where in fact $d is a different type of object which will then hold the
link to the real one. I am still looking for $d to be an object I can do
all of the checks on that are provided by int or DateTime as appropriate
... the object needs to exist before the 'new' in order to know if you
need the first or second type of $initial code ... or we make typed
properties only work one way or the other?

-- 
Lester Caine - G8HFL
-----------------------------
Contact - http://lsces.co.uk/wiki/?page=contact
L.S.Caine Electronic Services - http://lsces.co.uk
EnquirySolve - http://enquirysolve.com/
Model Engineers Digital Workshop - http://medw.co.uk
Rainbow Digital Media - http://rainbowdigitalmedia.co.uk