AW: [PHP-DEV] [RFC] Nullsafe calls

> -----Ursprüngliche Nachricht----- > Von: Josh Watzman [mailto:jwatzman@fb.com] > Gesendet: Mittwoch, 10. Dezember 2014 19:43 > An: Robert Stoll > Cc: PHP internals > Betreff: Re: [PHP-DEV] [RFC] Nullsafe calls > > On Dec 10, 2014, at 8:17 AM, Robert Stoll <php@tutteli.ch> wrote: > > > First of all, I like the RFC, I think as well that it is a useful > > feature for PHP and I already have it on my wish list > > ;) > > > > Yet, either I misunderstand the section about short circuiting or I propose to change the > > behaviour. > > > > "If $obj is null, when $obj?->foo(..) executes, the arguments will still be > > evaluated." > > > > IMO that is wrong. It should not evaluate the arguments since the nullsafe operator > > (sometimes called "safe navigation" > > operator in other languages - which is the better wording IMO, maybe > > change it? But that is just a detail) is just syntactic sugar for making the call only if > > $bj is not null. So the following: > > > > [...] > > > > Take a look at the "short circuit" section where I specifically address this. It was > done to make it easier to reason about in a > side-effect-ful language like PHP. With this behavior, when you see > > $x?->f(g(), h()) > > you don't have to worry about thinking whether g() and h() will actually be evaluated or > not -- only the call to f() itself, > which is explicitly marked as nullsafe (i.e., might not happen). It also comes down to what you > mean by "not making the > method call when $x is null" -- we in fact don't make the method call, but we still > prepare everything as if we were going to, > and just decide not to do it at the last moment. > > I feel pretty strongly that this is the correct behavior. It may sound strange when talking > about isolated examples like this, > but in the real-world code I've seen, it is the least confusing. (I'll see if I can > dig up a better example instead of just citing > nebulous "real-world code" ;)) > > Josh > > > -- > PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: > http://www.php.net/unsub.php I stick with it, evaluating it does not make sense IMO. If I want to execute it in any case then I would do something like this currently $g = g(); $h = h(); if($x !== null){ $x->foo($g, $h)->bar(baz()); } And with the ?-> operator: $g = g(); $h = h(); $x?->foo($g, $h)?->bar(baz()); Where I do not expect that baz() is called. You wrote it will be confusing for the user if the arguments would not be evaluated. I do not think so, telling them it is a short form for ($x !== null ? $x->foo() : null) is very easy and straight forward for the user to pick up. Therefore, please dig up a better example. Right now, I think it is a good idea in general to add a nullsafe operator to PHP but not only in the way mentioned.