Re: [RFC] Asymmetric visibility

> On Aug 11, 2022, at 7:38 PM, André Hänsel <andre@webkr.de> wrote: > > Nicolas Grekas wrote: > >> But I'm also wondering about the use case where asymmetry would be >> useful in practice now that we have readonly? >> I voted against readonly at the time because it didn't address >> cloning, and also because it deprives end-users vs code authors IMHO >> (alike "final"). I would have very much prefered asymmetric >> visibility back then. But now that we are here, what are the use cases? > > Isn't it (obviously?) to have setters that ensure all invariants of the > properties are met? I'd still rather have Property Accessors as > described in https://wiki.php.net/rfc/property_accessors, but I > think > AV is a step in the right direction. > > As for readonly, I don't understand why that exists at all. For immutability. Here is one reference on immutability offered up by the google gods: https://hackernoon.com/5-benefits-of-immutable-objects-worth-considering-for-your-next-project-f98e7e85b6ac <https://hackernoon.com/5-benefits-of-immutable-objects-worth-considering-for-your-next-project-f98e7e85b6ac> Immutability goes hand-in-hand with Functional Programming (FP.) While PHP is not a functional programming language, PHP developers can gain benefits from an FP style for which immutability is beneficial. Also from the google gods, if you are unfamiliar with FP: https://alvinalexander.com/scala/fp-book/benefits-of-functional-programming/ <https://alvinalexander.com/scala/fp-book/benefits-of-functional-programming/> Hope this helps. -Mike P.S. Also, the Internals list's very own Larry Garfield is a huge advocate for FP in PHP, voilà: https://leanpub.com/thinking-functionally-in-php https://www.garfieldtech.com/taxonomy/term/95 > Yes, it's > good that readonly properties can only be set from within the class, > but only once, so you get setters that throw when called a second time, > which I think is very, VERY unexpected behavior. Calling them > "readonly" is also somewhat misleading because of course the objects > assigned to those "readonly" properties can still be mutated, they can > just not be reassigned. > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: https://www.php.net/unsub.php >