Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:129088
Precedence: list
MIME-Version: 1.0
Date: Wed, 05 Nov 2025 13:53:34 +0100
To: Ben Ramsey <ben@benramsey.com>
Cc: Seifeddine Gmati <azjezz@carthage.software>, internals@lists.php.net
Subject: Re: [PHP-DEV] [RFC][Discussion] use construct (Block Scoping)
In-Reply-To: <AF76B1AB-CC48-4B37-8782-E7E6A87B0E3D@benramsey.com>
References: <CAFyg4HhrzQrE-q8D6WVkyq9tY+hzR=8rXiXLDPYpNKdYeydrVA@mail.gmail.com>
 <AF76B1AB-CC48-4B37-8782-E7E6A87B0E3D@benramsey.com>
Message-ID: <d90b6a325922b1a6b47976253e1a9ce1@bastelstu.be>
Content-Type: text/plain; charset=UTF-8;
 format=flowed
Content-Transfer-Encoding: 8bit
From: tim@bastelstu.be (=?UTF-8?Q?Tim_D=C3=BCsterhus?=)

Hi

Am 2025-11-04 03:08, schrieb Ben Ramsey:
> In general, I support this RFC. I’d like to see examples from other 
> programming languages, though. You mention C# and Hack above. Can you 
> elaborate in the RFC on how they implement this functionality? What 
> about other programming languages? I know some (Rust maybe?) are scoped 
> to blocks by default.

Please have a look at Seifeddine's previous reply to Edmond 
(https://news-web.php.net/php.internals/129076) and my reply to Arnaud 
that I just sent (https://news-web.php.net/php.internals/129087).

There are two things to consider when comparing against other 
programming languages. PHP's semantics do not exactly fit any of these, 
which means that transferring some concept from another programming 
language directly does not work.

1. Scoping:

Many programming languages with explicit variable declarations are block 
scoped. This includes Rust (which you correctly mentioned), but also C, 
C++, Java, JavaScript (with let and const). Some of them allow shadowing 
variables from the scope and some don't.

2. Handling of Lifetimes:

As I mentioned in my reply to Arnaud, PHP is pretty unique in the list 
of programming languages with automated memory management in that it 
does not primarily use an “unpredictable” garbage collector for memory 
management, but instead uses reference counting with reliable destructor 
semantics (that are documented). This is different from e.g. Java where 
the so-called “finalizers” run at an unpredictable point in time when 
the GC feels like cleaning up an object. PHP's semantics are close to 
those of C++ (where this kind of memory management is called RAII) or 
Rust.

For this reason, PHP just needs some generic “syntactic sugar” for 
`unset()` that is compatible with all existing functionality using 
`__destruct()` for those RAII semantics.

Best regards
Tim Düsterhus