Re: Regarding array_shift()/array_unshift()

On Wed, Jun 2, 2021, at 6:15 PM, Mike Schinkel wrote: > > On Jun 2, 2021, at 7:07 PM, Larry Garfield <larry@garfieldtech.com> wrote: > > > > On Wed, Jun 2, 2021, at 5:59 PM, Mike Schinkel wrote: > >>> On Jun 2, 2021, at 4:25 AM, Jordi Boggiano <j.boggiano@seld.be> wrote: > > > >>> IMO for unshift() it'd be fine to return a new array, but when processing a > >>> list of things in a FIFO pattern I often used array_shift() to get the first "job" out of > >>> the array. If $array->shift() returns a new array then how do I access the first item? > >> > >> That is a really excellent point, something I did not think to consider > >> given how rarely I use array_shift(). > >> > >> But your comment causes me to ponder a number of follow up questions, > >> some of which are tangential. If any reader feels these tangents are > >> worth discussing please make another email and quote my relevant > >> comments so we can have a dedicated thread for each. > >> > >> 1.) Given Nikita's position that it would only be viable to offer a > >> syntax that simulates method calling for arrays if the methods > >> themselves are immutable can you envision a solution for allowing > >> $array->shift() functionality that would address getting both element > >> and shifted array without resorting to by-reference parameters? > > > > $list->head() (returns first item) > > $list->tail() (returns all items but the first one) > > I assume $list->tail() would still have the O(<n>) problem in PHP, though? > > -Mike If implemented like an array, yes. If implemented in a more efficient way in C, potentially not. Or at least a smaller constant multiplier with n. (If something is O(n) but the cost per in is very small, then it being O(n) is not a big deal. If the cost per n is huge, it's a very huge deal.) --Larry Garfield