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Date: Thu, 4 Mar 2021 14:53:30 +0100
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To: =?UTF-8?Q?Micha=C5=82_Marcin_Brzuchalski?= <michal.brzuchalski@gmail.com>
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Subject: Re: [PHP-DEV] [RFC] New in initializers
From: nikita.ppv@gmail.com (Nikita Popov)

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On Thu, Mar 4, 2021 at 6:21 AM Micha=C5=82 Marcin Brzuchalski <
michal.brzuchalski@gmail.com> wrote:

> Hi Nikita,
>
> =C5=9Br., 3 mar 2021, 16:04 u=C5=BCytkownik Nikita Popov <nikita.ppv@gmai=
l.com>
> napisa=C5=82:
>
>> Hi internals,
>>
>> I would like to propose allowing the use of "new" inside various
>> initializer expressions: https://wiki.php.net/rfc/new_in_initializers
>>
>> In particular, this allows specifying object default values for properti=
es
>> and parameters, and allows the use of objects as attribute arguments.
>>
>> The RFC is narrow in scope in that it only adds support for "new". An
>> extension to other call kinds should be straightforward though.
>>
>
> The reflection mechanism for properties, constants and parameters is not
> described in RFC but I do believe it should for constants part. Correct m=
e
> if I'm wrong there.
>
> The reflection for ReflectionProperty::getDefaultValue the same for
> ReflectionParameter is similar and I get that it possibly should evaluate
> the value on each call. But what about constants which by their nature
> don't change?
> Does that mean that each time ReflectionClass::getConstant is called the
> value is already evaluated and the return value always refer to the same
> object instance. Is that right? I guess it is.
>
> IMO it deserves to be described in the RFC.
>
> In general I love the proposal was especially thinking of it for static
> variables.
>
> Cheers,
> Micha=C5=82 Marcin Brzuchalski
>

I've added a section that describes reflection methods. It works exactly as
you say.

There is one interesting case though: How should
ReflectionObject::newInstanceWithoutConstructor() work? In the current
implementation, it will still evaluate the property defaults, including new
expressions. This makes sense to me, but I can also see an argument that
this method should not evaluate them -- however, in that case I believe it
should not initialize any properties at all (leave them in "uninitialized"
state). Populating property default values depending on what kind of
expression they contain seems like a no-go to me.

@Ben Ramsey: Yes, it's possible to use nested new. Generally, all supported
constant expressions can be freely combined.

Regards,
Nikita

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