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Subject: Re: [PHP-DEV] [RFC] [Discussion] Support object type in BCMath
In-Reply-To: <b232c9f1-aad9-4ef3-8f23-d0cb2deb0baf@rwec.co.uk>
Date: Sun, 7 Apr 2024 00:07:08 +0900
Cc: internals@lists.php.net
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Message-ID: <B6391516-7680-4B7C-BFBA-D5DEE274F030@sakiot.com>
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To: "Rowan Tommins [IMSoP]" <imsop.php@rwec.co.uk>
From: saki@sakiot.com (Saki Takamachi)

Hi Rowan and folks,

> While this is an intriguing idea, it only solves a narrow set of use =
cases. For instance:
> - The class might want different behaviour for different operations; =
e.g. Money(42, 'USD') + Money(42, 'USD') should give Money(84, 'USD'); =
but Money(42, 'USD') * Money(42, 'USD') should be an error.
> - Properties might need to interact with each other; e.g. Distance(2, =
'metres') + Distance(2, 'feet') could result in Distance(2.6096, =
'metres'); but if you calculate one property at a time, you'll end up =
with Distance(4, 'metres'), which is clearly wrong.
> The fundamental problem is that it ignores the OOP concept of =
encapsulation: how an object stores its internal state should not define =
its behaviour. Instead, the object should be able to directly define =
behaviour for the operations it supports.

Thank you for pointing it out. Given what Tim and you mentioned, trying =
to make BCMath\Number have more than just "a value" is probably the =
wrong approach. (Except for some properties for rationality of =
calculation)

Inheritable classes are attractive, but there are too many problems to =
solve to make them a reality, some of which are probably impossible to =
solve. I explored various possibilities, but in the end, I think making =
it a final readonly class is the healthiest option.



To you all:
The discussions thus far have been reflected in the RFC. I would be very =
happy if you could check it out. (Thanks Tim, the <PHP> tag is very easy =
to read.)
https://wiki.php.net/rfc/support_object_type_in_bcmath

Regards.

Saki=