Unwrap reference after foreach

This seems like a good opportunity to go one step further and have loops create a new scope, which would automagically handle the unwrapping with out worrying about the edge cases. Obviously, this would be a bigger BC break, but one worth considering.

Sounds reasonable, but this is too much a BC break for my taste.
PHP doesn’t have a lot of scopes, and at a quick glance, this would increase them by 33%.

I /know/ I wrote code using the last iterated index/key of a loop.

That said, I also /know/ I wrote code using the value-by-reference after the loop, so I’m neither keen on voting +1 on the actual proposal. Granted though, it’d be an easy fix if there’s already a condition in the loop breaking its continuation.

Regards,
Mike

On Fri, Aug 13, 2021 at 11:20 AM Claude Pache claude.pache@gmail.com
wrote:

Le 13 août 2021 à 15:28, Nikita Popov nikita.ppv@gmail.com a écrit :

Hi internals,

I'd like to address a common footgun when using foreach by reference:
https://wiki.php.net/rfc/foreach_unwrap_ref

This addresses the issue described in the big red box at
https://www.php.net/manual/en/control-structures.foreach.php. While
this is
"not a bug" (as our bug tracker can regularly attest), it's rather
unexpected, and we could easily avoid it...

Regards,
Nikita

Hi,

I don’t like the split of semantics between simple and complex variables.
It makes the language more inconsistent, therefore more difficult to reason
about.

On the other hand, using a complex variable as reference in that context
should be very rare outside obfuscation code contests.

Therefore, I suggest to deprecate (and later remove) the ability to use of
a complex variable as reference in that context. That would solve the
inconsistency issue.

—Claude

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Hi,

I know I don't have an actual vote (voting karma it is), but it's a +1 from
me as well.

I like Trevor's suggestion of scoping variables within loops and this would
be a first step towards it.

Speaking of, i hope that one day we can support javascript-style let in php
:) like
foreach($it as let &$v){}
but that's a discussion for another thread (and i'm sure it has been
discussed before, i haven't actually checked though)

On Sat, 14 Aug 2021 at 15:23, Hossein Baghayi hossein.baghayi@gmail.com
wrote:

I'd like to address a common footgun when using foreach by reference:
https://wiki.php.net/rfc/foreach_unwrap_ref

Hello,
I had a question regarding this.
Wouldn't it be possible to limit $value's scope to only foreach's
block then discard it? Unless it was already defined elsewhere.

foreach($nice_stuff as &$value) {} //we are done here and no need to keep
value around.

echo $value; // $value is Undefined here.

$value = null;
foreach($stuff as &$value) {} //we can keep the value here since it doesn't
belong to foreach.

echo $value; // prints some fancy pancy stuff

well today you can do
foreach($it as &$value){...} unset($value);

• which is pretty close, but it will break with
  $value="initial";foreach($it as &$value){...}unset($value); echo $value;
  here $value will not be "initial", it will be undefined, however you CAN
  do

$value="initial";(function()use(&$it){foreach($it as
&$value){...}unset($value);})(); echo $value;

and it will still contain "initial" and here the unset is even unnecessary,
but yeah..
usually people do not go to such lengths to get a contained variable scope
^^

On Sat, 14 Aug 2021 at 15:23, Hossein Baghayi hossein.baghayi@gmail.com
wrote:

I'd like to address a common footgun when using foreach by reference:
https://wiki.php.net/rfc/foreach_unwrap_ref

Hello,
I had a question regarding this.
Wouldn't it be possible to limit $value's scope to only foreach's
block then discard it? Unless it was already defined elsewhere.

foreach($nice_stuff as &$value) {} //we are done here and no need to keep
value around.

echo $value; // $value is Undefined here.

$value = null;
foreach($stuff as &$value) {} //we can keep the value here since it doesn't
belong to foreach.

echo $value; // prints some fancy pancy stuff

Le 13 août 2021 à 15:28, Nikita Popov nikita.ppv@gmail.com a écrit :

Hi internals,

I'd like to address a common footgun when using foreach by reference:
https://wiki.php.net/rfc/foreach_unwrap_ref

This addresses the issue described in the big red box at
https://www.php.net/manual/en/control-structures.foreach.php. While this
is
"not a bug" (as our bug tracker can regularly attest), it's rather
unexpected, and we could easily avoid it...

Regards,
Nikita

A case that should be mentioned in the RFC is destructuring:

foreach ($foo as [ $x, &$y ]) { /* .... */ }

https://3v4l.org/A5Vi7

I assume that the reference in $y would be unwrapped after the loop?

I clarified to the RFC to say that
a) unwrapping also occurs if the loop is left using break, continue, goto
etc.
b) unwrapping occurs for array destructuring targets under the same
limitation of "simple variables only". So yes, $y would be unwrapped in
your example.

Regards,
Nikita

Hi internals,

I'd like to address a common footgun when using foreach by reference:
https://wiki.php.net/rfc/foreach_unwrap_ref

This addresses the issue described in the big red box at
https://www.php.net/manual/en/control-structures.foreach.php. While this
is "not a bug" (as our bug tracker can regularly attest), it's rather
unexpected, and we could easily avoid it...

As the discussion has died down, I plan to open voting on this RFC soon.

I have to admit that I'm less convinced of this than I was originally,
because there's a surprising number of edge cases involved. The behavior is
more intuitive on the surface, but things get more complicated when you
look at detailed language semantics.

I have ultimately decided to withdraw this proposal.

Regards,
Nikita