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Date: Tue, 16 Dec 2025 22:31:06 +0000
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Subject: Re: [PHP-DEV] [RFC] Context Managers
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From: imsop.php@rwec.co.uk ("Rowan Tommins [IMSoP]")

On 16/12/2025 21:40, Matthew Weier O'Phinney wrote:
> I want block scoping; I have been bitten by accidental 
> re-assignment within a block many times, and hate having to come up 
> with an ever-so-slightly-different variable name to disambiguate. I 
> don't care if it's this proposal or the "let" proposal in terms of how 
> the engine handles it - but the syntax of "using (expression => $var)" 
> isn't going to get my vote due to how easily it can be written 
> incorrectly.


I want block scoping too. I don't think *either* of the current 
proposals achieves that elegantly.

Context Managers aren't even trying to achieve it. Block scoping of the 
context variable is a minor design detail which was added after the RFC 
was shared with the list. You could in theory write a Context Manager 
which took a value in its constructor and spat it out unchanged from its 
"enter" method, but it would be a weird and wasteful way to create a 
local variable.

The let() block proposal *is* about block scoping, but only for its own 
special kind of block. I am not convinced by the reasons given for using 
this unusual approach.

I would much rather we copy the precedent established by ALGOL 60 years 
ago, and have variable declarations as statements which can appear in 
the body of any block. In particular, I would probably just copy 
JavaScript: allow "let $foo;" and "let $foo=expression;" anywhere, and 
disallow use in the "temporal dead zone" between the start of the block 
and the declaration.


However, I would also like Context Managers; which are a separate 
feature, giving nice sugar for re-usable try-finally blocks.


-- 
Rowan Tommins
[IMSoP]