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Date: Wed, 22 Dec 2021 01:47:44 +0100
Message-ID: <CAB-Bujau5x0EZHo+pzzNcfq_KXLKQpiqbgfzRqExHRJabBp-Ow@mail.gmail.com>
To: Jordan LeDoux <jordan.ledoux@gmail.com>
Cc: Dan Ackroyd <Danack@basereality.com>, Stanislav Malyshev <smalyshev@gmail.com>, 
	PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] User Defined Operator Overloads (v0.6)
From: andreas@dqxtech.net (Andreas Hennings)

On Tue, 21 Dec 2021 at 23:20, Jordan LeDoux <jordan.ledoux@gmail.com> wrote=
:
>
>
>
> On Tue, Dec 21, 2021 at 5:47 AM Andreas Hennings <andreas@dqxtech.net> wr=
ote:
>>
>> I see the "Implied Operators" section.
>> I assume this means that a new instance will be created, and stored on
>> the same variable, _if_ the original operator is written in an
>> immutable way (which it should be)?
>>
>> E.g.
>>
>> $money =3D new Money(5);
>> $orig =3D $money;
>> $m2 =3D $money + new Money(2);
>> assert($money =3D=3D=3D $orig);  // Checking object identity.
>> assert($m2 !=3D=3D $orig);
>> $money +=3D new Money(1);  // Equivalent to $money =3D $money + new Mone=
y(1);
>> assert($money !=3D=3D $orig);
>> assert($orig->amount() =3D=3D=3D 5);
>>
>> I think we need a strong recommendation to implement operators as immuta=
ble.
>
>
>  Yes. The documentation for operator overloads should be much larger than=
 this RFC, and if this passes my focus for the rest of 8.2 will be on two t=
hings:
>
> - Working on a few smaller follow up RFCs (sorting/ordering enum, polymor=
phic handler resolution)
> - Working to help on the documentation of this feature
>
> All of the examples in the documentation should be for immutable implemen=
tations, and there should be an explicit recommendation for immutable imple=
mentations as well. With operators, mutable versions are created with the o=
perators under the "Implied" section instead of by creating an immutable im=
plementation of the operator itself.

Right. But even for the "implied" operators, I would say "mutable"
should refer to the variable, but not to the object.
This is what I tried to communicate with the code example.

>
> Jordan