Re: Inline typecasting / typehinting for classes and interfaces

Hi, after reading this mail: Is it just me or is a userspace implementation really that trivial? function ensure($object, $class) { if ($object instanceof $class) { return $object; } throw new InvalidArgumentException(sprintf('Object is not of type %s', $class)); } And then instead of all a new syntax $myObject = ensure($another->foobar, MyType::class); // [1] Did I miss something. Regards, Sebastian [1] There was another RFC that suggested this special property. 2012/8/15 Nikita Popov <nikita.ppv@gmail.com> > On Wed, Aug 15, 2012 at 8:15 PM, Kris Craig <kris.craig@gmail.com> wrote: > > On Wed, Aug 15, 2012 at 4:48 AM, Anthony Ferrara <ircmaxell@gmail.com > >wrote: > > > >> Stan, > >> > >> On Wed, Aug 15, 2012 at 3:57 AM, Stan Vass <sv_forums@fmethod.com> > wrote: > >> > >> > Hi! > >> >> > >> >> I agree with you. The one case where this syntax may be very useful > is > >> if > >> >>> we want to implement class casting. So introduce a pair of magic > >> methods > >> >>> > >> >> > >> >> I do not think we want to implement class casting. I'm not sure how > >> >> class casting even makes sense - if the object is of one class, how > can > >> >> you just make it into another class by casting? If you mean > >> >> "casting" > >> >> actually returns another object of different class, then just make a > >> >> method for that that returns that object, I do not see how obscuring > the > >> >> purpose of this operation with unobvious syntax would help. > >> >> > >> > > >> > The discussion is starting to drift very far from my original > proposal. > >> > > >> > Instead of trying to guess what I mean, can't people just refer to my > >> very > >> > simple definitive proposed behavior? > >> > > >> > >> My point was that what I posted was the only way that I can see for the > >> original proposal to be useful. > >> > >> Anthony > >> > > > > Though I'm clearly in the minority on this, I for one think this proposal > > does have more merit than is being argued. There seems to be general > > agreement all around that this would provide a benefit as it pertains to > > code readability-- Not just by humans, but theoretically by doc/etc > parsers > > as well. > > > > This is where we get into arbitrary, subjective territory. To me, that > > benefit in and of itself is sufficient to warrant this feature. To many > of > > you, it is not enough. > > > > The tie-breaker for me is the fact that, though the benefits are modest, > > there's really no noticeable cost, either. The argument seems to, > > essentially, break down as follows: "This feature isn't worth our time." > > .... "Yes, it is!" .... "No, it isn't." > > Every feature has a cost, even if that cost is just maintaining the > code. Doing language changes for minority use cases, which already > have sensible solutions, doesn't make much sense. > > Another aspect here is that there is no reasonable syntax for this > feature, at least I can't think of one: > > * The syntax $foo = (InterfaceName) $container->service is > completely out of question. It looks like a cast, but wouldn't > actually do a cast. > * Same is to be said about `InterfaceName $foo = > $container->service`. This syntax implies that the $foo variable will > always be of type InterfaceName, even if it is later reassigned. It's > not a sensible syntax for a one time validation > * The other three syntaxes that were mentioned were just as unclear. > E.g. $foo = $container->service as InterfaceName again looks > like a > strange cast syntax and $foo = $container->service is > InterfaceName > looks like the assignment should evaluate to a boolean (i.e. is > is > some kind of instanceof). > > On the other hand, the current ways of accomplishing the same goal are > well-established and easy to understand: > > * Using a docblock: /** @var $foo IntefaceName **/ > * Using an assertion: assert($foo instanceof InterfaceName). > > I think that the assertion is a rather concise and clear way to do > this. It is much more obvious than some new and obscure `$foo = > (InterfaceName $container->service)` syntax. > > Nikita > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php > >