Re: [RFC] Safe Casting Functions

So, what exactly changes here if we have a second parameter or just return null by default? It doesn’t make any difference, it’s just another way to write it: to_int($a, $default) or to_int($a) ?? $default Also, if you want exceptions, you always can wrap a userland function around it — but I’d rather not wrap an userland function around something throwing an exception… inefficient and weird. Thanks, Bob > Am 22.10.2014 um 12:27 schrieb Dmitry Stogov <dmitry@zend.com>: > > "null" or "false" return value would make these functions not really > useful, because they won't guarantee to return desired type. > > printf("%d\n", to_int("abcd")); // will print 0 > > The only reliable option to support wrong input is exceptions. > On the other hand, exceptions maybe difficult to use or inefficient. > We may avoid exceptions throwing, if provide a default value: > > function to_int(mixed $a , int $default_value = null): int; > function to_double(mixed $a , double $default_value = null): double; > function to_string(mixed $a, string $default_value = null): string; > > Thanks. Dmitry. > > On Wed, Oct 22, 2014 at 12:37 PM, Bob Weinand <bobwei9@hotmail.com> wrote: > >> I know we have that already discussed a lot now, but I’d like to expose my >> points on the return value here: >> >> I imagine code like (supposing that we ever will have scalar typehints): >> >> function acceptsInt (int $i = null) { >> if ($i === null) { >> $i = 2 /* default value */; >> } >> /* do something with $i */ >> } >> >> When we return false: >> acceptInt(($tmp = to_int($_GET["userinput"])) === false ? null : $tmp); >> >> When we throw an exception: >> try { >> acceptInt(to_int($_GET["userinput"])); >> } catch (CastingException $e) { >> acceptInt(null); >> } >> >> When we just return null: >> acceptInt(to_int($_GET["userinput"])); >> >> Also, when we want to pass a default value defined outside of the >> function, it’s a lot easier now with the coalesce operator: >> acceptInt(to_int($_GET["userinput“]) ?? 2 /* default value */); >> >> >> Also, independently of possible scalar typehints: >> >> Generally exceptions are also a bad idea as the casts probably will be >> used on external input and exceptions are **not** a way to handle malformed >> user input. Really not. >> Furthermore, false is a bad idea in the same sense (if we get scalar type >> hints once), because people then might just catch the EngineException… >> >> Also, null means "no value"; that’s exactly what we need. If the >> to_{type}() functions cannot return a meaningful value, just return "no >> value", that means null. And not false, which is a real value. >> >> That’s why I strongly feel that null is the only true thing to return here. >> >> Thanks, >> Bob >> >>> Am 21.10.2014 um 00:57 schrieb Andrea Faulds <ajf@ajf.me>: >>> >>> Good evening, >>> >>> I am presenting a new RFC to add a set of three functions to do >> validated casts for scalar types: >>> >>> https://wiki.php.net/rfc/safe_cast >>> >>> Please read it. >>> >>> Thanks! >>> -- >>> Andrea Faulds >>> http://ajf.me/