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Date: Tue, 30 Sep 2025 16:13:50 +0100
Message-ID: <CAGBsUrcPL4uPu_ehRJOC5qqu8OAK+=_a4KuhXiRhzkLMrTe_vQ@mail.gmail.com>
Subject: Re: [PHP-DEV] [Discuss] Add PDO disconnect() and isConnected()
To: Andrey Andreev <narf@devilix.net>
Cc: Robert Wolf <rposky@gmail.com>, PHP internals <internals@lists.php.net>
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From: tekiela246@gmail.com (Kamil Tekiela)

On Tue, 30 Sept 2025 at 15:42, Andrey Andreev <narf@devilix.net> wrote:
>
> On Tue, Sep 30, 2025 at 4:56=E2=80=AFPM Kamil Tekiela <tekiela246@gmail.c=
om> wrote:
>>
>> I find this proposal to be a backwards step in the age when we are
>> moving away from resources and their explicit closure. We have
>> disabled this in PHP 8.0 for curl_close(), imagedestroy(),
>> openssl_pkey_free(), shmop_close() and xml_parser_free(). Sure,
>> mysqli_close() still works, but the whole extension is mostly a
>> historical artefact and a bunch of bad design choices due to what that
>> extension is (quick replacement of mysql_* API). PDO was designed much
>> better and it deliberately avoided the foot gun that is explicit
>> connection closure. I really wish we would not introduce bad design
>> choices into the language, and because of this, I wish this proposal
>> were unsuccessful.
>
>
> All of the foot gun examples you listed are such because that historic de=
sign pattern *required* explicit resource frees, and they are foot guns bec=
ause it is easy to forget doing that.
> Also, mysqli_close() is the only one that handles a stateful network conn=
ection and not a local resource, which is a good reason why it still works.
>
> There are legitimate use cases where you may want to explicitly and immed=
iately close a network connection, even if PHP would do it eventually.
>
> Cheers,
> Andrey.

By foot gun, I meant that when such a method exists, the developer can
never be sure that the PDO object is in a consistent state. As long as
the PDO object is accessible, closing it in one place in the code
means that there exists another place in the code where the object is
accessible but unusable. This is what gets so many mysqli users.

Another issue is that if you call disconnect on PDO object, but you
still have PDOStatement with unfetched data, you silently lose the
data or get an exception. This situation is more difficult to
accidentally arrive at, but still possible. You also lose the ability
to call methods such as PDOStatement::execute(). This is not possible
today, but by adding disconnect method we introduce a way in which
this is possible.

PDO isn't a new extension. It has done well without such a function
for many years. Maybe there are legitimate use cases for this, but
there are also alternatives. Pretty much every time I hear the
argument that it would be nice if PDO had it, I can reply with: you
can just design your code in a way that doesn't need it.

The disconnect method isn't needed for long-running scripts. PHP will
disconnect automatically when it determines that the connection is no
longer needed, and only then. It's the responsibility of the developer
to ensure that they don't keep variables around that aren't necessary
anymore.