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Date: Wed, 15 Jul 2020 18:38:26 -0300
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To: Marco Pivetta <ocramius@gmail.com>
Cc: Larry Garfield <larry@garfieldtech.com>, php internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC][Discussion] Objects can be declared falsifiable
From: marcio.web2@gmail.com (Marcio Almada)

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Hi!

Hey Larry,
>
> wrote:
>
> > 1) return null, which is a non-type, and thus you need to make the retu=
rn
> > type ?User or User|null, which means the caller *must* always check it'=
s
> > nullness.
> >
> > Allowing an object to falsify itself is a 4th,  more type-safe option.
> It
> > lets you return an object that both fails a boolean check (like null) b=
ut
> > also has default values in it for the base case.  A user object likely
> > wouldn't use that, but a value object like an Address very well could.
> >
> > Until we can support for-reals monads (which would require enums and
> > generics to do properly; the former is possible the latter is very hard=
),
> > it's the best option we have for more type-safe returns.
> >
>
> Adding a "falsey" state for code that expects `is_object($foo) =3D=3D=3D =
(bool)
> $foo` seems to be a massive BC break to me, and reduces type safety of
> boolean operators (and checks) by expanding the `object` type and all
> operators and expressions that can interact with it.
>
>
I've heard a few times that this would reduce type safety. Well, on runtime
it really does, the same way when you use null in a wrong manner, but
with static analysis tools in place I wouldn't expect a formal proof that
it's impossible to analyze that kind of code. Unless we are eval'ing or
declaring variables dynamically... I'll try to research a bit on that.

What would be the default static analyser used for PHP today? Psalm?

Ty,
M=C3=A1rcio

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