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Date: Thu, 15 May 2025 18:49:11 +0200
Message-ID: <CAB-BujauX9LDj8YJAdTrBvk4_iaCwT0fJC2EVsjzA15oNS4JCA@mail.gmail.com>
Subject: Re: [PHP-DEV] [RFC] Clone with v2
To: Stephen Reay <php-lists@koalephant.com>
Cc: Volker Dusch <volker@tideways-gmbh.com>, 
	"Matthew Weier O'Phinney" <mweierophinney@gmail.com>, php internals <internals@lists.php.net>, 
	=?UTF-8?Q?Tim_D=C3=BCsterhus?= <tim@bastelstu.be>
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From: andreas@dqxtech.net (Andreas Hennings)

On Thu, 15 May 2025 at 13:56, Stephen Reay <php-lists@koalephant.com> wrote=
:
>
>
>
>
> > On 15 May 2025, at 16:44, Andreas Hennings <andreas@dqxtech.net> wrote:
> >
> > =EF=BB=BFOn Thu, 15 May 2025 at 08:24, Stephen Reay <php-lists@koalepha=
nt.com> wrote:
> > [..]
> >>
> >>
> >> I may be missing something here..
> >>
> >> So far the issues are "how do we deal with a parameter for the actual =
object, vs new properties to apply",  "should __clone be called before or a=
fter the changes" and "this won't allow regular readonly properties to be m=
odified".
> >>
> >> Isn't the previous suggestion of passing the new property arguments di=
rectly to the __clone method the obvious solution to all three problems?
> >
> > What exactly should happen then?
> > Would the __clone() method be responsible for assigning those propertie=
s?
> > Or does the __clone() method get the chance to alter the values before
> > they are assigned?
> > (this would mean they have to be passed by reference)
> > I think this last option is the best, because the values in the array
> > can be changed without any readonly constraints.
> >
> > Another option I was thinking of would be to call __clone() after the
> > changes are applied, and pass both the original object and the array
> > of changes as first parameter.
> > But I think this is a dead end.
> >
> > -- Andreas
> >
> >>
> >> There's no potential for a conflicting property name, the developer ca=
n use the new property values in the order they see fit relative to the log=
ic in the __clone call, and it's inherently in scope to write to any (unloc=
ked during __clone) readonly properties.
> >>
> >>
> >>
> >> Cheers
> >>
> >> Stephen
> >>
> >>
> >>
> >
>
> I would suggest that the __clone method should be directly responsible fo=
r making any changes, just as it is now when it comes to deep cloning or re=
setting values.
>
> Yes I realise it means developers need to then opt in and provide the fun=
ctionality to support `clone $foo with(bar: "baz")` or whatever syntax is u=
sed.

I don't really like this.
It would mean that if you add an empty __clone() method, it would
prevent all of the automatic setting of values.

>
> If the properties are public properties, there's nothing stopping someone=
 writing their own clone_with() in userland now;  If someone is using reado=
nly properties I'd suggest they want to specifically manage updates to thos=
e properties themselves anyway.

But they already do that in the ->withXyz() methods.

A public non-readonly property can be set from anywhere without
validation or clean-up, so by default the __clone() method would want
to leave it alone.
A readonly or non-public property can only be initialized from within
the class, so the ->withSomething() method would be the place for
cleanup and validation.
The default behavior of an empty __clone() method should therefore be
to just allow all of the properties being set as they would be without
a __clone() method.

>
> Additionally it means "clone with" would be usable for non-public propert=
ies at the discretion of the developer writing their code.

This is already the case, because that "clone with" for non-public
properties can only happen from within methods of the same class
(hierarchy).

-- Andreas

>
> The mental model is also very clear with this: copy the object in memory,=
 and then call __clone(), with the arguments passed to the clone action - w=
hich may be none in the case of code that doesn't accept any clone argument=
s.  The only change from the current model is that it *may* be passing argu=
ments.
>
> Cheers
>
> Stephen
>
>
>