Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:67927
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: error (pb1.pair.com: domain sclinternet.co.uk from 209.85.212.53 cause and error)
MIME-Version: 1.0
Sender: tom@sclinternet.co.uk
In-Reply-To: <CAKUjMCV1mShSH1bqPyb788oPYGyQyFXewcotihDpMYt8usxzjw@mail.gmail.com>
References: <CAM+1YOz823PCdixmWorg3c37Z3LazcFQ7FHYoKg_Z_tEaw+=QA@mail.gmail.com>
	<CAKUjMCV1mShSH1bqPyb788oPYGyQyFXewcotihDpMYt8usxzjw@mail.gmail.com>
Date: Thu, 27 Jun 2013 10:04:29 +0100
Message-ID: <CAM+1YOwEY8YitkGij4SiYyBk7QAcL_Rfwz-n86y3F6Q3ouxxpw@mail.gmail.com>
To: RQuadling@gmail.com
Cc: PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=089e013a2746c3e2a704e01f0c7d
Subject: Re: [PHP-DEV] RFC Proposal: New assign value operator
From: tom@scl.co.uk (Tom Oram)

--089e013a2746c3e2a704e01f0c7d
Content-Type: text/plain; charset=ISO-8859-1

Hi Richard,

Thanks for your reply, the main reason would be operator overloading rather
than the typecasting example, the typecasting version is more for
consistency. I am also fairly that there might be situations where it would
be useful to set the value of a scalar while preserving the time and save
the need for checking the type first, however I do admit I can't think of a
concrete example.

The main thing I was thinking is I often find myself writing things like:

$obj->set(2);

$obj->setValue(5);

$obj->setX(4);

Where the object only really represent a single value, examples are things
like EmailAddress class, ZipCode class, MoneyValue class, etc.

Everytime I write something like one of the examples above I wish I could
simply write:

$email = 'tom@scl.co.uk';

and continue to use my EmailAddress class, however since PHP is loosely
type this replaces the object with a string, hence my suggesting for new
operator.


All the best,
Tom


On 26 June 2013 11:51, Richard Quadling <rquadling@gmail.com> wrote:

>
>
>
> On 25 June 2013 11:01, Tom Oram <tom@scl.co.uk> wrote:
>
>> Hi everyone,
>>
>> I've got an idea for an RFC proposal and from reading the instructions it
>> looks like I should run it past you guys first.
>>
>> I have not made any contributions to PHP before although I have made some
>> custom modifications in house in the past and while I'm no longer familiar
>> with the PHP code base I am confident I have the skills to implement this
>> should it be accepted.
>>
>> What I want to propose is a new assignment operator which rather than
>> setting the variable to completely new value it would update the value
>> while maintaining the type.
>>
>> The main motivation for this is for easy assignment to value objects aka
>> assignment operator overloading via a magic method (prehaps called
>> __assign).
>>
>> Here is an example ( for now I will use the PASCAL style assignment
>> operator := as the new operator as it is a know assignment operator and
>> currently not used in PHP):
>>
>> // For a class defined like so...
>> class MoneyValue
>> {
>>     protected $amount;
>>
>>     public function __assign($value)
>>     {
>>         $this->amount = $value;
>>     }
>> }
>>
>> // The amount could then be assigned using the new operator like this
>>
>> $price = new MoneyValue();
>>
>> $price := 29.99;
>>
>> While the primary focus would be for assignment operator overloading as I
>> just displayed in the previous example, for consistency it could be used
>> with scalar values to preserve type like so:
>>
>> // $str is now a string
>>
>> $str = 'Original String';
>>
>> // Using the new assignment variable would cast the value being assigned
>> to
>> the variable's type
>> // (in this case a string). So
>>
>> $str := 7;
>>
>> // Would be the equivalent to
>> //
>> // $str = (string) 7;
>> //
>> // $str === "7"
>>
>>
>> Another quick example:
>>
>> $num = 5;
>>
>> $num := '12';
>>
>> // Equivalent to
>> //
>> // $num = (int) '12';
>> //
>> // $num === 12;
>>
>> So what do you guys think?
>>
>> If I get a good response I'll look into how to create a proper RFC and
>> start trying to work out how to implement it.
>>
>> Many thanks and look forward to some responses,
>> Tom
>>
>
> Hi.
>
> I'm not going to comment on the merits as such, but I'd be interested in
> knowing what problem this RFC would solve?
>
> Considering PHP has type juggling scalars, it would SEEM (I may have
> missed the point) that this could result in data loss when the enforced
> conversion results in 0/False/"".
>
> $num = 8;
> $num := "data from user"; // 0
>
> Unless that is the expected behaviour.
>
> Where would this RFC change be used?
>
> And having said all of that, I'm not against it, just want to see what it
> would be useful for that isn't already part of PHP's toolbox.
>
> --
> Richard Quadling
> Twitter : @RQuadling
> EE : http://e-e.com/M_248814.html
> Zend : http://bit.ly/9O8vFY
>



-- 
****************************************************
PLEASE NOTE: For support requests please
use support@scl.co.uk instead of emailing
staff directly, this way your request is likely to
be dealt with more efficiently.
****************************************************
Tom Oram - SCL Internet Services
PO Box 8, Cardigan, Ceredigion, SA41 3YA
Website: http://www.scl.co.uk/
Tel: +44 (0) 1239 622 411
Fax: +44 (0) 1239 622428
Company Reg. No. 2441708
****************************************************

--089e013a2746c3e2a704e01f0c7d--