Re: Support rewinding of generators

On Wed, Feb 26, 2020 at 4:03 PM Rowan Tommins <rowan.collins@gmail.com> wrote: > Hi Nikita, > > On 26 February 2020 11:47:14 GMT+00:00, Nikita Popov > <nikita.ppv@gmail.com> wrote: > >There is a relatively simple (at least conceptually) way to make > generators > >rewindable: Remember the original arguments of the function, and basically > >"re-invoke" it on rewind(). > > This is an interesting idea. > > There is a gotcha though, neatly demonstrated by your example: > > >function map(callable $function, iterable $iterable): \Iterator { > > foreach ($iterable as $key => $value) { > > yield $key => $function($value); > > } > >} > > If the $iterable passed in is anything other than an array, > re-invoking the function won't actually rewind it. Point of order: foreach() always rewinds the array / Iterator it gets. The code does work correctly under the proposed scheme. Nikita