Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:111019
User-Agent: Cyrus-JMAP/3.3.0-dev0-613-g8a73ad6-fm-20200709.001-g8a73ad6e
Mime-Version: 1.0
Message-ID: <132a2f9c-331c-48c9-8c15-f0f7c9392341@www.fastmail.com>
In-Reply-To: 
 <CAKuGYLT-31Bjav6bKBYDBqPc6wb41FzebzoSWBmt9+4=OdRAYA@mail.gmail.com>
References: <21C5073D-3F39-49DA-8686-E027AE780793@joshbruce.dev>
 <CAKuGYLT-31Bjav6bKBYDBqPc6wb41FzebzoSWBmt9+4=OdRAYA@mail.gmail.com>
Date: Wed, 15 Jul 2020 08:39:08 -0500
To: "php internals" <internals@lists.php.net>
Content-Type: text/plain
Subject: Re: [PHP-DEV] [RFC][Discussion] Objects can be declared falsifiable
From: larry@garfieldtech.com ("Larry Garfield")

On Tue, Jul 14, 2020, at 11:48 PM, Matthew Brown wrote:
> On Tue, 14 Jul 2020 at 19:59, Josh Bruce <josh@joshbruce.dev> wrote:
> 
> > Implement an interface and magic method to allow objects to represent
> > false (or empty) while still be valid instances of the custom object (type).
> >
> > https://wiki.php.net/rfc/objects-can-be-falsifiable <
> > https://wiki.php.net/rfc/objects-can-be-falsifiable>
> >
> > If you saw the latest from this morning, not much has changed except
> > hopefully improved formatting and now being the official mix of things.
> >
> > If this is your first time, the cues are taken from:
> >
> > - __toString()
> > - Stringable
> > - and __toArray() (not accepted or approved yet)
> >
> > Thank you for all the feedback and patience so far, appreciate it!
> >
> > Cheers,
> > Josh
> 
> 
> I'm not sure I love this (mostly from a static analysis standpoint).
> 
> It means that there would exist some `$foo` with the property that `$foo &&
> !$foo` evaluates to true.
> 
> That seems to be a bad place for a language to go, and it would increase
> the false-negative rate of static analysis tools.

I don't see how that would happen.  What non-pathological case would allow for $foo && !$foo == true?

(I know you could do something stupid like return random_int() from __toBool(), but I'm ignoring that as "you're dumb so of course your code is dumb.)

From the RFC, I don't quite get this line: 

"Further, the union type bool|Falsifiable will be dynamically added at run time to any object implementing the reserved __toBool() method, which would allow stdClass() objects to be defined as Falsifiable also. "

What's that about?  

"(Including __construct() replacing old style constructors in PHP 7.)" - __construct replaced old-style constructors in PHP 5. :-)

I think the truth tables have a formatting error; check the last line that goes wider than the rest.  Also, watch out for "smart quotes" in the string parts.  Also, YAY summary tables!

--Larry Garfield