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Date: Wed, 26 Jun 2013 11:51:06 +0100
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To: Tom Oram <tom@scl.co.uk>
Cc: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] RFC Proposal: New assign value operator
From: rquadling@gmail.com (Richard Quadling)

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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

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