Re: [RFC] Add is_list(mixed $value): bool to check for list-like arrays

> On Dec 21, 2020, at 16:15, Mike Schinkel <mike@newclarity.net> wrote: > >> On Dec 20, 2020, at 9:09 PM, Ben Ramsey <ben@benramsey.com> wrote: >> >>> On Dec 19, 2020, at 19:43, tyson andre <tysonandre775@hotmail.com> >>> wrote: >>> >>> It can be useful to verify that the assumption that array keys are >>> consecutive integers is correct, both for data that is being passed >>> into a module or for validating data before returning it from a >>> module. However, because it's currently inconvenient to do that, this >>> has rarely been done in my experience. >> >> I think there are some places where is_list() could be >> unintuitive to >> those who don’t understand some of the idiosyncrasies of PHP. >> >> For example, with >> >> $a = ['foo', 'bar', 'baz’]; >> >> is_list() will return true, >> but if you run $a through asort(), >> is_list() will return false >> because the keys are no longer >> consecutive integers, but is there any doubt this is still a list? >> Maybe in a pure sense, it’s not, but I think this could be confusing. >> >> But now, if we do >> >> $b = array_merge($a, ['qux', 'quux']); >> >> $b is now back to being a list, so >> is_list($b) returns true. >> >> While I understand the convenience is_list() provides--I >> myself have >> implemented the opposite of this numerous times (e.g., >> is_dict())--it comes close to implying a data type that PHP >> doesn’t >> have, and I think this could give a false sense of type-safety-ness >> when using this function to check whether something is a 0-indexed >> array. >> >> Cheers, >> Ben >> > > Would either is_zero_based() or is_zero_indexed() be a reasonable > name instead? > > -Mike > > P.S. See https://en.wikipedia.org/wiki/Zero-based_numbering I don’t think changing the name changes my concern, but as Tyson pointed out: > These idiosyncrasies of php and unintuitive behaviors existed prior > to this RFC. I’m generally +1 on this RFC, but as I think about it, maybe there is a problem with the name. If we choose to introduce a pure list construct at some point, then is_list() may cause confusion (or maybe it won’t, if it can be made to return true for a zero-indexed, standard PHP array *and* a list, whatever that might look like in the language). Cheers, Ben

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