On Fri, Jun 26, 2020 at 12:45 AM Alex <alexinbeij...@gmail.com> wrote: > > Dear PHP Internals, > > I would like to propose a backwards-incompatible change to > SplFixedArray which fixes the strange and almost certainly unintended > behavior reported in Bug 79404 > (https://bugs.php.net/bug.php?id=79404). > > In short: Because SplFixedArray is an Iterator, and stores its own > iteration state, it cannot be used in nested foreach loops. If you > try, the inner loop will overwrite the iteration position of the outer > loop, so that the outer loop 'thinks' it is finished after the inner > loop finishes. > > To illustrate: > > $spl = SplFixedArray::fromArray([0, 1]); > foreach ($spl as $a) { > foreach ($spl as $b) { > echo "$a $b"; > } > } > > Only prints two lines: > > 0 0 > 0 1 > > The fix is to convert SplFixedArray to an IteratorAggregate, so each > nested foreach loop operates on a different iterator object and thus > nested loops don't interfere with each other. > > Now, it would be possible to do this while still defining key(), > current(), next(), etc. methods on SplFixedArray. However, that would > cause an even more insidious BC break, since these methods would no > longer work as formerly when called in the body of a foreach loop. > Therefore, I think it better to remove them. This may break a few > users' code, but in a way which will be easier for them to debug than > if the old methods were kept but subtly changed in behavior. > > Code to implement this change is here: > https://github.com/php/php-src/pull/5384/files > > Your comments will be appreciated, > Alex Dowad > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: https://www.php.net/unsub.php >
As someone who has patches in the SPL, I support the idea of this change. One gotcha of aggregates is iterator invalidation; are you sure the patch takes care of it? If you have an array of size 3, get an iterator, iterate to offset 2, shrink the size with `setSize`, and use the iterator at offset 2, will everything be okay? -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: https://www.php.net/unsub.php
