PHP RFC: Make the iterator_*() family accept all iterables

• Version: 1.0
• Date: 2022-06-21
• Author: Tim Düsterhus, duesterhus@woltlab.com
• Status: Implemented
• Target Version: PHP 8.2
• Implementation: https://github.com/php/php-src/commit/7ae7df5b4601f3f0ce45a27324fb9c6ebcbfc9ed
• First Published at: http://wiki.php.net/rfc/iterator_xyz_accept_array

PHP's iterator_*() family currently only accept \Traversables (i.e. they reject plain arrays). This is unnecessarily limiting.

Specifically this concerns the iterator_to_array() and iterator_count() functions. While each of them has an array-specific counterpart, the fact that one needs to choose either the array-specific variant or the everything-but-array variant makes writing code the deals with arbitrary iterables unnecessarily verbose.

As an example: Allowing iterator_to_array() to take an array, makes it much easier to write functions accepting an iterable and processing it using array_map() et al:

function before(iterable $foo) {
    if (!is_array($foo)) {
        $foo = iterator_to_array($foo);
    }
 
    return array_map(strlen(...), $foo);
}
function after(iterable $foo) {
    $foo = iterator_to_array($foo);
 
    return array_map(strlen(...), $foo);
}

The $iterator parameter of iterator_to_array() and iterator_count() should be widened from \Traversable to iterable (i.e. to \Traversable|array).

Specifically if this RFC is accepted the following shall hold:

This function is not part of this proposal, because it is non-obvious how to define the behavior for arrays, given that it does not pass the Iterator to the callback by default.

None, this is a purely type widening change.

next PHP 8.x

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Anything that isn't iterator_to_array() or iterator_count().

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Each vote requires a 2/3 majority.

Voting opened 2022-07-05 14:30 UTC and closes on 2022-07-19 14:45 UTC.

iterator_to_array: Change the type of iterator_to_array()’s $iterator parameter from \Traversable to iterable?
Real name	Yes	No
asgrim (asgrim)
bwoebi (bwoebi)
colinodell (colinodell)
crell (crell)
jwage (jwage)
kalle (kalle)
kguest (kguest)
levim (levim)
marandall (marandall)
nicolasgrekas (nicolasgrekas)
ocramius (ocramius)
reywob (reywob)
salathe (salathe)
santiagolizardo (santiagolizardo)
sergey (sergey)
svpernova09 (svpernova09)
timwolla (timwolla)
trowski (trowski)
weierophinney (weierophinney)
Final result:	17	2
This poll has been closed.

iterator_count: Change the type of iterator_count()’s $iterator parameter from \Traversable to iterable?
Real name	Yes	No
asgrim (asgrim)
bmajdak (bmajdak)
bwoebi (bwoebi)
colinodell (colinodell)
crell (crell)
jwage (jwage)
kalle (kalle)
kguest (kguest)
levim (levim)
nicolasgrekas (nicolasgrekas)
ocramius (ocramius)
reywob (reywob)
salathe (salathe)
santiagolizardo (santiagolizardo)
sergey (sergey)
svpernova09 (svpernova09)
timwolla (timwolla)
trowski (trowski)
weierophinney (weierophinney)
Final result:	17	2
This poll has been closed.

https://github.com/php/php-src/pull/8819

https://github.com/php/php-src/commit/7ae7df5b4601f3f0ce45a27324fb9c6ebcbfc9ed

• Pre-RFC discussion: https://externals.io/message/117979
• PoC implementation: https://github.com/php/php-src/pull/8819
• Similar previous RFC that proposed adding new functions with an iterable_* prefix: https://wiki.php.net/rfc/iterable_to_array-and-iterable_count
• Stack Overflow asking for iterable_to_array(): https://stackoverflow.com/q/44587973/782822

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