Re: [RFC] Keep type of reference params

---- En vie, 08 may 2020 23:40:22 +0200 Bob Weinand <bobwei9@hotmail.com> escribió ---- > > Am 04.05.2020 um 10:53 schrieb Manuel Canga <php@manuelcanga.dev>: > > > > Hi internals, > > > > > > > > I would like to present a possible new RFC( "keep type of reference params" ) > > for your > > > > consideration. > > > > > > > > Firstly, an example: > > > > > > > > ``` > > > > <?php > > > > > > > > function my_array_shift( array & $array ) { > > > > $array = "string"; > > > > } > > > > > > > > $array = [ 0, 1, 2, 3, 4 ]; > > > > > > > > my_array_shift($array); > > > > > > > > count( $array ); > > > > ``` > > > > > > > > The result of this code is a warning( in count line ) because of $array is a string. > > > > However, I think it should be an error or exception when a string is assigned to $array > > var. > > > > In my opinion, $array var would have to keep its type when function ends. > > > > > > > > What is your opinion ? Do you see it useful ? > > > > Thanks and I'm sorry for my English( I'm a Spanish ). > > > > Regards > > > > -- > > > > Manuel Canga > > Hey Manuel, > > the primary issue (apart from the BC break) here is leaking the reference across the function > boundary. > > function a(array &$a) { > $GLOBALS["globalA"] = &$a; > } > > funcition b() { > $GLOBALS["globalA"] = 10; > } > > $a = 1; > a($a); > b(); > // $a is magically changed to 10 > > Yes, you can here verify, that $a is an array at the function boundaries, but you cannot > afterwards. > > If we had proper inout parameters (which do not leak a reference, but assign the value of the > variable (in callee scope) back to the passed variable from caller), then we could easily enforce > it. > > But as it stands now, this is not an option. (Especially due to the false promise this seems > to make.) > > Bob Thanks Bob, that was a great example I explain...I am very forgetful, so it's very easy for me to write somethink like this: ``` function filter_something( &string $to_filter) { $to_filter = strtolower($to_lower); $to_filter = sanitize_this($to_filter); ..... } filter_something($my_string); ``` Sometimes, one of these functions can returns a false|null|numeric|... instead of expected type. Also, If any function in 'filter_somethid' would throw an exception, value in $to_filter would finish inconsistent However, with: ``` function filter_something( inout string $to_filter) { $to_filter = strtolower($to_lower); $to_filter = sanitize_this($to_filter); ..... } filter_something(inout $my_string); ``` PHP could in the end produce exception when any function in filter_something modify type of $my_string or PHP could keep value of $to_filter as well if any function throwed an exception. Regards -- Manuel Canga