Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:121854
MIME-Version: 1.0
References: <6566989F.7010305@adviesenzo.nl> <34dada8e-7f2a-4d94-b7df-d9d3c7b2f3ce@app.fastmail.com>
 <F200E6CF-5116-4361-AB5C-CDD67F2E2021@koalephant.com> <CAPzBOBPLK3rQwqYsfgF3nS6=nT1qTdz-pzVpgNFRmXd7Jh9oSA@mail.gmail.com>
In-Reply-To: <CAPzBOBPLK3rQwqYsfgF3nS6=nT1qTdz-pzVpgNFRmXd7Jh9oSA@mail.gmail.com>
Date: Wed, 29 Nov 2023 09:55:59 +0100
Message-ID: <CANS-=pfpzNwzO2b+rfD+wHk-3wDBtZ1vDOafuZRR5wwX1d-tFA@mail.gmail.com>
To: Robert Landers <landers.robert@gmail.com>
Cc: Stephen Reay <php-lists@koalephant.com>, php internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary="000000000000b89fbe060b46b5e4"
Subject: Re: [PHP-DEV] What is the prevailing sentiment about extract() and
 compact() ?
From: kjarli@gmail.com (Lynn)

--000000000000b89fbe060b46b5e4
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Wed, Nov 29, 2023 at 9:20=E2=80=AFAM Robert Landers <landers.robert@gmai=
l.com>
wrote:

> On Wed, Nov 29, 2023 at 8:19=E2=80=AFAM Stephen Reay <php-lists@koalephan=
t.com>
> wrote:
> >
> >
> >
> > > On 29 Nov 2023, at 09:58, Larry Garfield <larry@garfieldtech.com>
> wrote:
> > >
> > > On Tue, Nov 28, 2023, at 7:49 PM, Juliette Reinders Folmer wrote:
> > >> L.S.,
> > >>
> > >> What with all the drives towards cleaner code, how do people feel
> > >> nowadays about `extract()` and `compact()` still being supported ?
> > >>
> > >> Both have alternatives. The alternatives may be a little more
> cumbersome
> > >> to type, but also make the code more descriptive, lessens the risk o=
f
> > >> variable name collisions (though this can be handled via the $flags =
in
> > >> extract), prevents surprises when a non-associative key would be
> > >> included in an array and lessens security risks when used on
> untrusted data
> > >
> > > *snip*
> > >
> > >> I can imagine these could be candidates for deprecation ? Or limited
> > >> deprecation - only when used in the global namespace ?
> > >>
> > >> For now, I'm just wondering how people feel about these functions.
> > >>
> > >> Smile,
> > >> Juliette
> > >
> > > extract() has very limited use in some kinds of template engine, whic=
h
> use PHP require() as a template mechanism.  I don't think compact() has a=
ny
> uses.
> > >
> > > I very recently was just reminded that these even exist, as i had to
> tell one of my developers to not use them.  I think it was compact() he w=
as
> trying to use.  I vetoed it.
> > >
> > > I would not mind if they were removed, but I don't know how large the
> BC impact would be.  They'd probably need a long deprecation period, just
> to be safe.
> > >
> > > --Larry Garfield
> > >
> > > --
> > > PHP Internals - PHP Runtime Development Mailing List
> > > To unsubscribe, visit: https://www.php.net/unsub.php
> > >
> >
> > Hi,
> >
> > While I think I understand the goal behind this, I think you're missing
> some factors here.
> >
> > Regarding use-cases for compact: the most common one I can think of fro=
m
> my work, is for passing multiple local variables as context to a logging
> function, but I'd be surprised if its not also used to build faux hash
> structures too.
> >
> > If your goal is to achieve an associative array (i.e a poor mans hash)
> of known variable names, using compact in php8+ has *less* risk of
> uncaught/unexpected errors than building it manually. Passing an undefine=
d
> name (i.e. due a typo, or it just not being defined) produces a warning
> regardless of whether you build the array manually or pass the name(s) to
> compact(). Providing an array key name that doesn't match the variable na=
me
> (e.g. due to a typo, or a variable being renamed) will produce no error
> when building the array manually, but will produce a warning with compact=
().
> >
> > IDEs (e.g. PHPStorm/IDEA+PHP plugin) can already understand that the
> names passed to compact are a variable name, and make changes when a
> variable is renamed via the IDE. They simply cannot do the same for plain
> array keys.
> >
> > Due to how variable scope works, the only way to re-implement compact()
> with the same key-typo-catching behaviour as a function in userland would
> be something that requires the user to pass the result of
> get_defined_vars() to every call.
> >
> > So no, I don't think compact() should be deprecated, what I think
> *should* happen, is to promote the current warning on undefined variables=
,
> to an error, as per
> https://wiki.php.net/rfc/undefined_variable_error_promotion. Whether this
> is a foregone conclusion or not, I don't know because that RFC doesn't
> mention compact() specifically.
> >
> >
> > extract(), as Larry points out has historically been used by 'pure php'
> style template systems, in a manner that's generally "safe". Personally I=
'm
> less inclined to use this behaviour now (i.e. I'd prefer to access named =
&
> typed properties from a template than arbitrary local variable names) but=
 I
> don't think that's enough of a case to remove it, because just like with
> compact, by nature of how variable scope works, it's very
> difficult/impossible to re-implement this in userland, in a way that's
> reusable and doesn't involve using worse constructs (e.g. eval'ing the
> result of a function)
> >
> > I think there's possibly an argument to be made for improvements, such
> as changing the default mode of extract to something besides
> EXTR_OVERWRITE, or to have checks in place preventing the overwrite of
> superglobals.
> >
> >
> > Cheers
> >
> >
> > Stephen
>
> FWIW, I use compact all the time, usually like this:
>
> try {
>   // do stuff
> } catch(Throwable $exception) {
>   $this->logger->error("failed to do stuff", compact('exception'));
>   throw $exception;
> }
>
> But thanks for the reminder to finish the nameof RFC, I was waiting
> until after 8.3 to avoid the "trying to rush it to get into 8.3"
> shenanigans that happened to another RFC around the same time. If
> nameof passes, then it could make this more obvious when refactoring:
>
> try {
>   // do stuff
> } catch(Throwable $exception) {
>   $this->logger->error("failed to do stuff", compact(nameof($exception)))=
;
> }
>
> Robert Landers
> Software Engineer
> Utrecht NL
>
> --
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: https://www.php.net/unsub.php
>
>
My main concern with compact and extract is the counterintuitive usage of
variable names, which is also why I've personally broken production after
changing a variable name. If there is another way of using compact in a way
where it's used without string and with dollar sign, I won't have a problem
with it. I still find `compact(nameof($exception))` a little confusing
personally though. I have the feeling that the wish is to have a nice
syntactic sugar for compact, not sure about extract though. Extract for me
is somewhat of a security concern as it will make it easy to implicitly
overwrite variables from a local scope if the array being used is filled
elsewhere. Someone adding an array key in another layer of code in an
application can cause different behavior on a totally unrelated place when
there's a variable collision, and there's no way to detect this when adding
(or removing) a key from the array.

I'm all for getting rid of extract. For compact I'd like to explore
alternative solutions before outright deprecating. I'm still in favor of
seeing it gone in its current form though.

--000000000000b89fbe060b46b5e4--