Re: Re: RFC: CachedIterable (rewindable, allows any key&repeating keys)

On Tue, Jun 8, 2021 at 6:22 PM tyson andre <tysonandre775@hotmail.com> wrote: > > 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 Ǐ��S�9�"��K > > d�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 �O�?~�xs�6=h�e > 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 > Based on a recent comment you made on GitHub, it seems like CachedIterable eagerly creates the datastore instead of doing so on-demand. Is this correct?