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Date: Fri, 28 Jun 2024 00:11:06 +0200
To: "Jordan LeDoux" <jordan.ledoux@gmail.com>
Cc: "Saki Takamachi" <saki@sakiot.com>, "Gina P. Banyard" <internals@gpb.moe>,
 internals@lists.php.net
Subject: Re: [PHP-DEV] Overriding GMP objects
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From: rob@bottled.codes ("Rob Landers")

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On Thu, Jun 27, 2024, at 23:46, Jordan LeDoux wrote:
>=20
>=20
> On Thu, Jun 27, 2024 at 2:35=E2=80=AFPM Rob Landers <rob@bottled.codes=
> wrote:
>> __
>>=20
>>=20
>> On Thu, Jun 27, 2024, at 06:07, Saki Takamachi wrote:
>>>=20
>>> I agree with Gina. Being able to change the class of a computed resu=
lt of an inherited child class causes several problems.
>>>=20
>>> The points raised in the `BCMath\Number` discussion can be summarize=
d as follows.
>>>=20
>>> - If it is possible to perform calculations on parent Class and chil=
d Class, what should the resulting class be?
>>=20
>> Ask the class what it wants to be?
>>=20
>>> - Multiplying the distance class and the speed class should give you=
 the time class.
>>=20
>> That would depend on the library=E2=80=99s implementation.=20
>>=20
>>> - Similarly, multiplying two distance classes together should yield =
an area class.
>>=20
>> See above.=20
>>=20
>>> - If only child classes have a property that should be specified in =
the constructor, how do you determine the value of this property in the =
result class? Perhaps it is possible to determine the value of the prope=
rty, but in that case the commutativity of the computation should be los=
t.
>>=20
>> This can be handled via the child class in static methods, per the li=
brary specifications.
>=20
> How is the library supposed to do that in the absence of operator hand=
ler functions that can be overridden, or at least called when an operato=
r is encountered?
>=20
> Jordan

That=E2=80=99s what this email is about: adding those functions to the b=
ase GMP class as static protected methods.

A time class would look something like:

static protected add(GMP $left, GMP $right) {
  if($left instanceof self && $right instanceof self) return new self(pa=
rent::add($left, $right));
  throw new LogicException('can only add time to time');
}

=E2=80=94 Rob
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<!DOCTYPE html><html><head><title></title><style type=3D"text/css">p.Mso=
Normal,p.MsoNoSpacing{margin:0}</style></head><body><div><br></div><div>=
<br></div><div>On Thu, Jun 27, 2024, at 23:46, Jordan LeDoux wrote:<br><=
/div><blockquote type=3D"cite" id=3D"qt" style=3D""><div dir=3D"ltr"><di=
v dir=3D"ltr"><br></div><div><br></div><div class=3D"qt-gmail_quote"><di=
v dir=3D"ltr" class=3D"qt-gmail_attr">On Thu, Jun 27, 2024 at 2:35=E2=80=
=AFPM Rob Landers &lt;rob@bottled.codes&gt; wrote:<br></div><blockquote =
class=3D"qt-gmail_quote" style=3D"margin-top:0px;margin-right:0px;margin=
-bottom:0px;margin-left:0.8ex;border-left-width:1px;border-left-style:so=
lid;border-left-color:rgb(204, 204, 204);padding-left:1ex;"><div class=3D=
"qt-msg-4281734687375525032"><div><u></u><br></div><div><div><br></div><=
div><br></div><div>On Thu, Jun 27, 2024, at 06:07, Saki Takamachi wrote:=
<br></div><blockquote type=3D"cite" id=3D"qt-m_-4281734687375525032qt"><=
div><br></div><div>I agree with Gina.&nbsp;Being able to change the clas=
s of a computed result of an inherited child class causes several proble=
ms.<br></div><div><br></div><div>The points raised in the `BCMath\Number=
` discussion can be summarized as follows.<br></div><div><br></div><div>=
-&nbsp;If it is possible to perform calculations on parent Class and chi=
ld Class, what should the resulting class be?<br></div></blockquote><div=
><br></div><div>Ask the class what it wants to be?<br></div><div><br></d=
iv><blockquote type=3D"cite" id=3D"qt-m_-4281734687375525032qt"><div>-&n=
bsp;Multiplying the distance class and the speed class should give you t=
he time class.<br></div></blockquote><div><br></div><div>That would depe=
nd on the library=E2=80=99s implementation.&nbsp;<br></div><div><br></di=
v><blockquote type=3D"cite" id=3D"qt-m_-4281734687375525032qt"><div>-&nb=
sp;Similarly, multiplying two distance classes together should yield an =
area class.<br></div></blockquote><div><br></div><div>See above.&nbsp;<b=
r></div><div><br></div><blockquote type=3D"cite" id=3D"qt-m_-42817346873=
75525032qt"><div>-&nbsp;If only child classes have a property that shoul=
d be specified in the constructor, how do you determine the value of thi=
s property in the result class?&nbsp;Perhaps it is possible to determine=
 the value of the property, but in that case the commutativity of the co=
mputation should be lost.<br></div></blockquote><div><br></div><div>This=
 can be handled via the child class in static methods, per the library s=
pecifications.<br></div></div></div></blockquote><div><br></div><div>How=
 is the library supposed to do that in the absence of operator handler f=
unctions that can be overridden, or at least called when an operator is =
encountered?<br></div><div><br></div><div>Jordan<br></div></div></div></=
blockquote><div><br></div><div>That=E2=80=99s what this email is about: =
adding those functions to the base GMP class as static protected methods=
.<br></div><div><br></div><div>A time class would look something like:<b=
r></div><div><br></div><div>static protected add(GMP $left, GMP $right) =
{<br></div><div>&nbsp; if($left instanceof self &amp;&amp; $right instan=
ceof self) return new self(parent::add($left, $right));<br></div><div>&n=
bsp; throw new LogicException('can only add time to time');<br></div><di=
v>}<br></div><div><br></div><div id=3D"sig121229152">=E2=80=94 Rob<br></=
div></body></html>
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