Hi internals, > I've created a new RFC https://wiki.php.net/rfc/cachediterable adding > CachedIterable, > which eagerly evaluates any iterable and contains an immutable copy of the > keys and values of the iterable it was constructed from > > This has the proposed signature: > > ``` > final class CachedIterable implements IteratorAggregate, Countable, > JsonSerializable > { > public function __construct(iterable $iterator) {} > public function getIterator(): InternalIterator {} > public function count(): int {} > // [[$key1, $value1], [$key2, $value2]] > public static function fromPairs(array $pairs): CachedIterable {} > // [[$key1, $value1], [$key2, $value2]] > public function toPairs(): array{} > public function __serialize(): array {} // [$k1, $v1, $k2, $v2,...] > public function __unserialize(array $data): void {} > > // useful for converting iterables back to arrays for further processing > public function keys(): array {} // [$k1, $k2, ...] > public function values(): array {} // [$v1, $v2, ...] > // useful to efficiently get offsets at the middle/end of a long iterable > public function keyAt(int $offset): mixed {} > public function valueAt(int $offset): mixed {} > > // '[["key1","value1"],["key2","value2"]]' instead of '{...}' > public function jsonSerialize(): array {} > // dynamic properties are forbidden > } > ``` > > Currently, PHP does not provide a built-in way to store the state of an > arbitrary iterable for reuse later > (when the iterable has arbitrary keys, or when keys might be repeated). It > would be useful to do so for many use cases, such as: > > 1. Creating a rewindable copy of a non-rewindable Traversable > 2. Generating an IteratorAggregate from a class still implementing Iterator > 3. In the future, providing internal or userland helpers such as > iterable_flip(iterable $input), iterable_take(iterable $input, int $limit), > iterable_chunk(iterable $input, int $chunk_size), iterable_reverse(), etc > (these are not part of the RFC) > 4. Providing memory-efficient random access to both keys and values of > arbitrary key-value sequences > > Having this implemented as an internal class would also allow it to be much > more efficient than a userland solution > (in terms of time to create, time to iterate over the result, and total > memory usage). See https://wiki.php.net/rfc/cachediterable#benchmarks > > After some consideration, this is being created as a standalone RFC, and > going in the global namespace: > > - Based on early feedback on > https://wiki.php.net/rfc/any_all_on_iterable#straw_poll (on the namespace > preferred in previous polls) > It seems like it's way too early for me to be proposing namespaces in any > RFCs for PHP adding to modules that already exist, when there is no consensus. > > An earlier attempt by others on creating a policy for namespaces in > general(https://wiki.php.net/rfc/php_namespace_policy#vote) also did not pass. > > Having even 40% of voters opposed to introducing a given namespace (in > pre-existing modules) > makes it an impractical choice when RFCs require a 2/3 majority to pass. > - While some may argue that a different namespace might pass, > https://wiki.php.net/rfc/any_all_on_iterable_straw_poll_namespace#vote had > a sharp dropoff in feedback after the 3rd form. > I don't know how to interpret that - e.g. are unranked namespaces preferred > even less than the options that were ranked or just not seen as affecting the > final result.
A heads up - I will probably start voting on https://wiki.php.net/rfc/cachediterable this weekend after https://wiki.php.net/rfc/cachediterable_straw_poll is finished. Any other feedback on CachedIterable? Thanks, Tyson -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: https://www.php.net/unsub.php
