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Date: Mon, 5 Sep 2016 10:26:03 +0200
Message-ID: <CABdc3WqdTOid2BTGfpyVmNAca_9roxxx6AaQhKUPSYownO8MsA@mail.gmail.com>
To: PHP Internals List <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a114e507e5522c5053bbe6eb5
Subject: Re: [PHP-DEV] RFC - Immutable classes
From: michal@brzuchalski.com (=?UTF-8?Q?Micha=C5=82_Brzuchalski?=)

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I had a talk at Room11 and we discussed idea of `mutator` keyword.
There were some concerns using `mutator` as a keyword - that's because
immutable object is not being muted and also magically appeared `$clone`
would be confusing. There's an idea of creating clone before function begin=
s
and operating simply on `$this` while it's newly created clone from
immutable
object instance and the additional keyword for such method would be for eg.
`transformer`, so basically it may look like this:

immutable class Money {
    public $amount =3D 0;
    public $currency;
    public function __construct($amount, $currency) {
        $this->amount =3D $amount;
        $this->currency =3D $currency;
    }
    public transformer function amount($newamount) {
        $this->amount =3D $newAmount; // $this actually is newly created cl=
one
        return $this;
    }
}

$oneHundret =3D new Money(100, $eur);
$twoHundret =3D $oneHundret->amount(200);

How about that?


2016-09-05 4:21 GMT+02:00 Micha=C5=82 Brzuchalski <michal@brzuchalski.com>:

>
>
> 2016-09-04 22:38 GMT+02:00 Fleshgrinder <php@fleshgrinder.com>:
>
>> On 9/4/2016 2:29 PM, Micha=C5=82 Brzuchalski wrote:
>> >> Providing `mutator` | `mut` keyword as method modifier sounds liek a
>> good
>> >> idea,
>> >> althought passing `$clone` parameter as first additional param could
>> break
>> >> method declaration and would be misleading.
>> >>
>> >> Assuming mutator method is designed to  return mutated clone of
>> immutable
>> >> object
>> >> having `$clone` variable could be handled internally without breaking
>> >> method declaration.
>> >>
>> >> Such variable could be unlocked while in mutator method and locked on
>> >> return.
>> >> I was thinking about additional check if such mutator returns `$clone=
`
>> but
>> >> not `$this`
>> >> but I don't see the need of it - assuming there is no what to change =
in
>> >> some
>> >> circumstances ther would be also possible to return `$this`.
>> >>
>> >> The return type declaration `self` could increase readability, but
>> should
>> >> not be required,
>> >> as some developers doesn't already use return types.
>> >>
>> >
>> > It could look like in this gist
>> > https://gist.github.com/brzuchal/e7b721e22a19cca42ec0d1f597a23baf
>> >
>>
>> This is exactly how I meant it, yes. I actually prefer it if the
>> variable just exist in the context instead of passing it as first
>> argument. It's less obvious that it exists but the same could be said
>> about $this.
>>
>> Would it be possible to have this thing just in time instead of
>> automatically created in every mutator function?
>>
>>   public mutator function f() {
>>     if (condition) {
>>       $clone is created;
>>       return $clone;
>>     }
>>     return $this;
>>   }
>>
>> PS: I started overhauling the test cases and error messages and will
>> create a PR against your branch soon. I will start with the RFC
>> afterwards. Should I simply edit the RFC in the Wiki or should we manage
>> this somewhere else?
>>
>>
> You may begin with modifications on RFC eg. in a gist so we can all discu=
ss
> about it before putting on RFC, is that okay to you?
>
>
>> --
>> Richard "Fleshgrinder" Fussenegger
>>
>>
>
>
> --
> regards / pozdrawiam,
> --
> Micha=C5=82 Brzuchalski
> brzuchalski.com
>



--=20
regards / pozdrawiam,
--
Micha=C5=82 Brzuchalski
brzuchalski.com

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