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Date: Wed, 2 Nov 2022 21:51:16 -0400
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Cc: Claude Pache <claude.pache@gmail.com>,
 =?utf-8?Q?Micha=C5=82_Marcin_Brzuchalski?= <michal.brzuchalski@gmail.com>,
 php internals <internals@lists.php.net>
To: Marco Pivetta <ocramius@gmail.com>
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Subject: Re: [PHP-DEV] [RFC][Discussion] Objects can be declared falsifiable
From: josh@joshbruce.dev (Josh Bruce)

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Thank you all for the engagement so far.

(Note: All scalar types and one compound type can be cast as true or =
false natively - of the scalar and compound types, callable and object =
are the only two with no, native false representation.)

> Have you tried not initializing invalid objects? This could help you. =
Also that sounds more logical to me as I don't see any reasons to =
initialize invalid objects if it's a matter of simple validation =
instead.


I've tried valid objects (multiple approaches) - and I=E2=80=99m using =
the term valid loosely because the instances are not, technically, =
invalid in the strictest sense. I=E2=80=99m using =E2=80=9Cvalid=E2=80=9D =
and =E2=80=9Cinvalid=E2=80=9D as method names in the implementation =
because I don=E2=80=99t have a better word to describe the concept; =
still looking. If you'd like to hear more, please let me know and I can =
detail out other approaches, which are pretty standard.=20

I only used it as an example of what would be possible and trying to =
illustrate using a real world example of the problem-space.

With that said, the RFC isn=E2=80=99t meant to directly solve an =
implementation issue that can=E2=80=99t be solved any other way; it=E2=80=99=
s more syntax, style, and consistency (see note above).=20

Similar to:

function x(?SomeType $arg): ?SomeOtherType

Instead of:

function x(SomeType|null $arg): SomeType|null

Both are the same thing under the hood.

In that same spirit, totally opt-in - not required to use or you can get =
there some other way - similar to Marco=E2=80=99s comment around =
__toString.=20

For example, I actively avoid null and don=E2=80=99t use most =
null-related things available in PHP and tend to wrap objects, methods, =
and functions that might return null=E2=80=A6but, if you=E2=80=99re into =
null, don=E2=80=99t let me stop you. :)

(I also tend to wrap objects, methods, and functions that return bool =
and some other type to put them in a context where I get one or the =
other, but not either-or - file_put_contents, for example=E2=80=A6big =
fan of single return types.)

> The one situation in which I can think of where an object might =
legitimately have a falsey bool casting is if it represents a single =
value


I see that, though I don=E2=80=99t necessarily agree.

To use similar language, the object could represent a single, complex =
concept (especially through composition) - not just a single value.=20

A car without a blinker is still a car and usable for most things it was =
designed for - and there could be a fallback for the missing blinker; =
valid instance with a non-blocking deficiency: =
https://www.dmv.org/how-to-guides/hand-signals-guide.php

>>> P.S. I don't see it feasible to have objects that evaluate false in =
logical expressions.


I=E2=80=99m interested in more detail on this.=20

Feasible as in not possible to do easily? Not possible in general? Or, =
something else?=20

> For better or for worse (IMHO, for worse), `SimpleXMLElement` =
instances representing attributeless empty elements are already falsy, =
so yes, it is absolutely feasible.

Interesting use case. Haven=E2=80=99t used SimpleXMLElement enough to =
comment.

Interested to hear more.

> This is absolutely terrifying.

Not sure if this is referring to the SimpleXMLElement reference or =
beyond it. :)

Cheers,
Josh

> On Nov 2, 2022, at 2:09 PM, Marco Pivetta <ocramius@gmail.com> wrote:
>=20
> On Wed, 2 Nov 2022 at 18:51, Claude Pache <claude.pache@gmail.com> =
wrote:
>=20
>>=20
>>=20
>>> Le 2 nov. 2022 =C3=A0 09:12, Micha=C5=82 Marcin Brzuchalski <
>> michal.brzuchalski@gmail.com> a =C3=A9crit :
>>>=20
>>> P.S. I don't see it feasible to have objects that evaluate false in
>>> logical expressions.
>>=20
>> For better or for worse (IMHO, for worse), `SimpleXMLElement` =
instances
>> representing attributeless empty elements are already falsy, so yes, =
it is
>> absolutely feasible.
>>=20
>> =E2=80=94Claude
>=20
>=20
> This is absolutely terrifying.
>=20
> Marco Pivetta
>=20
> https://twitter.com/Ocramius
>=20
> https://ocramius.github.io/


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