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Date: Fri, 28 Jun 2024 17:13:58 -0700
Message-ID: <CAMrTa2E=gomoXakUgDJNL_JtOYV2NkRZ_1MUX_fsiuFk8Mq27Q@mail.gmail.com>
Subject: Re: [PHP-DEV] [RFC] Operator Overrides -- Lite Edition
To: Rob Landers <rob@bottled.codes>
Cc: internals@lists.php.net
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From: jordan.ledoux@gmail.com (Jordan LeDoux)

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On Fri, Jun 28, 2024 at 12:55=E2=80=AFPM Rob Landers <rob@bottled.codes> wr=
ote:

>
>
> 3. The private/protected distinction is fairly meaningless for the
> functions that implement overloads, because the privacy of the function i=
s
> ignored completely when it is executed to evaluate an operator.
>
>
> Hmm. I like the idea of protected, because it gives a structure to it tha=
t
> is apparent and usable right from the IDE. You just =E2=80=9Cfill in the =
blanks=E2=80=9D or
> stick with the default behavior.
>

I do not understand how the visibility has any impact on the usability you
are seeking to provide.

4. The `static` distinction is also fairly meaningless, as in PHP there is
> no situation possible where an operator overload can occur WITHOUT it
> operating on objects themselves.
>
>
> For this, that is the wrong approach. The actual behavior is on the type,
> not the instance. The object instances may not even know their value, the=
y
> merely represent the value.
>

A GMP object instance that does not know its value? What are you even
talking about? Can you show me some code explaining what you mean? I had
literally months of this argument for the operator overloads RFC, and
studied the overload implementations in six other languages as part of
writing that RFC, I feel like I understand this topic fairly well. But I do
not understand what you are saying here.


> 6. The `comparable` function you propose doesn't actually have an operato=
r
> it corresponds to. There is no operator in PHP for "is the left value
> comparable with the right value". There are operators for comparisons
> themselves, which I assume you meant, but a bool is insufficient as a
> return type for that.
>
>
> In the engine, there=E2=80=99s just a compare function for internal overr=
ides. So
> we just check that everyone agrees that the two objects are comparable an=
d
> then pass it on to =E2=80=9Cbusiness as usual.=E2=80=9D
>

 I'm aware of how the compare handler for class entries and zend_compare
interact. What I am saying is that your design is insufficient for <=3D>. Y=
ou
cannot return `false` from this method to mean uncomparable, and `true` to
mean comparable. The zend_compare function can validly return 0 or -1, with
the -1 being used for both less than OR greater than because the operands
are reordered to always be a less than comparison. Then 1, which normally
is used for greater than, is used to mean uncomparable.

If you alter GMP so that the compare handler directly calls the class entry
for this "comparable" function, you will be mixing multiple return semantic
meanings, assuming you can construct a way to make the values normalize. If
you implemented "comparable" in the way you are describing, $obj1 =3D=3D $o=
bj2
would ALWAYS be true, no matter what their values are, completely changing
the meaning of the equality operator for GMP.

As you are proposing this without any genuine expectation you can pass it,
this will be the last energy I will invest into helping.

Jordan

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<div dir=3D"ltr"><div dir=3D"ltr"><br></div><br><div class=3D"gmail_quote">=
<div dir=3D"ltr" class=3D"gmail_attr">On Fri, Jun 28, 2024 at 12:55=E2=80=
=AFPM Rob Landers &lt;rob@bottled.codes&gt; wrote:<br></div><blockquote cla=
ss=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid =
rgb(204,204,204);padding-left:1ex"><div class=3D"msg3306475242208035808"><u=
></u><div><div><br></div><br><blockquote type=3D"cite" id=3D"m_330647524220=
8035808qt"><div dir=3D"ltr"><div><div>3. The private/protected distinction =
is fairly meaningless for the functions that implement overloads, because t=
he privacy of the function is ignored completely when it is executed to eva=
luate an operator.<br></div></div></div></blockquote><div><br></div><div>Hm=
m. I like the idea of protected, because it gives a structure to it that is=
 apparent and usable right from the IDE. You just =E2=80=9Cfill in the blan=
ks=E2=80=9D or stick with the default behavior.=C2=A0</div></div></div></bl=
ockquote><div><br></div><div>I do not understand how the visibility has any=
 impact on the usability you are seeking to provide. <br></div><div><br></d=
iv><blockquote class=3D"gmail_quote" style=3D"margin:0px 0px 0px 0.8ex;bord=
er-left:1px solid rgb(204,204,204);padding-left:1ex"><div class=3D"msg33064=
75242208035808"><div><blockquote type=3D"cite" id=3D"m_3306475242208035808q=
t"><div dir=3D"ltr"><div><div>4. The `static` distinction is also fairly me=
aningless, as in PHP there is no situation possible where an operator overl=
oad can occur WITHOUT it operating on objects themselves.<br></div></div></=
div></blockquote><div><br></div><div>For this, that is the wrong approach. =
The actual behavior is on the type, not the instance. The object instances =
may not even know their value, they merely represent the value.<br></div></=
div></div></blockquote><div><br></div><div>A GMP object instance that does =
not know its value? What are you even talking about? Can you show me some c=
ode explaining what you mean? I had literally months of this argument for t=
he operator overloads RFC, and studied the overload implementations in six =
other languages as part of writing that RFC, I feel like I understand this =
topic fairly well. But I do not understand what you are saying here.<br></d=
iv><div>=C2=A0</div><blockquote class=3D"gmail_quote" style=3D"margin:0px 0=
px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div =
class=3D"msg3306475242208035808"><div><div></div><blockquote type=3D"cite" =
id=3D"m_3306475242208035808qt"><div dir=3D"ltr"><div><div>6. The `comparabl=
e` function you propose doesn&#39;t actually have an operator it correspond=
s to. There is no operator in PHP for &quot;is the left value comparable wi=
th the right value&quot;. There are operators for comparisons themselves, w=
hich I assume you meant, but a bool is insufficient as a return type for th=
at.<br></div></div></div></blockquote><div><br></div><div>In the engine, th=
ere=E2=80=99s just a compare function for internal overrides. So we just ch=
eck that everyone agrees that the two objects are comparable and then pass =
it on to =E2=80=9Cbusiness as usual.=E2=80=9D</div></div></div></blockquote=
><div><br></div><div>=C2=A0I&#39;m aware of how the compare handler for cla=
ss entries and zend_compare interact. What I am saying is that your design =
is insufficient for &lt;=3D&gt;. You cannot return `false` from this method=
 to mean uncomparable, and `true` to mean comparable. The zend_compare func=
tion can validly return 0 or -1, with the -1 being used for both less than =
OR greater than because the operands are reordered to always be a less than=
 comparison. Then 1, which normally is used for greater than, is used to me=
an uncomparable.</div><div><br></div><div>If you alter GMP so that the comp=
are handler directly calls the class entry for this &quot;comparable&quot; =
function, you will be mixing multiple return semantic meanings, assuming yo=
u can construct a way to make the values normalize. If you implemented &quo=
t;comparable&quot; in the way you are describing, $obj1 =3D=3D $obj2 would =
ALWAYS be true, no matter what their values are, completely changing the me=
aning of the equality operator for GMP.</div><div><br></div><div>As you are=
 proposing this without any genuine expectation you can pass it, this will =
be the last energy I will invest into helping.</div><div><br></div><div>Jor=
dan<br></div><div><br></div></div></div>

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