On 5 April 2016 at 11:57, Michał Brzuchalski <mic...@brzuchalski.com> wrote:
> Hi, > > 2016-04-05 12:13 GMT+02:00 Marco Pivetta <ocram...@gmail.com>: > > > Hi, > > > > On 5 April 2016 at 12:06, Michał Brzuchalski <mic...@brzuchalski.com> > > wrote: > > > >> Hi Marco, > >> > >> Ad. 1 it is posiible to redeclare in a sub-class final property as > >> non-final, here is some gist presenting my current impl working like: > >> https://gist.github.com/brzuchal/12ebda1efed59440a78ba43bff116728 > >> > > > > > It works with public, private and protected properties. > > > > Does this work for public properties as well? > > > > > >> Ad. 2. `final` means class variable (like static) or class instance > >> property can not change their reference, it is impossible to replace > zval > >> in such property, in my opinion `immutable` is object behavior when > using > >> some methods you receive newly created (cloned) object which is changed > >> exactly like `DateTimeImmutable` > >> http://php.net/manual/en/datetimeimmutable.add.php > >> > > > > I am aware of what `final` means in other languages, it just seems that > > everyone then needs to translate back and forth from `final` to > > `immutable`. In addition to that, `final` has different meaning in > > inheritance (re-used keyword), so this adds to the confusion for people > > unfamiliar with the feature. > > > > Wiki about Final in Java > https://www.wikiwand.com/en/Final_(Java)#/Final_variables says: > > # Final variables > A final variable can only be initialized once, either via an initializer or > an assignment statement. It does not need to be initialized at the point of > declaration: this is called a "blank final" variable. A blank final > instance variable of a class must be definitely assigned in every > constructor of the class in which it is declared; similarly, a blank final > static variable must be definitely assigned in a static initializer of the > class in which it is declared; otherwise, a compile-time error occurs in > both cases.[6] (Note: If the variable is a reference, this means that the > variable cannot be re-bound to reference another object. But the object > that it references is still mutable, if it was originally mutable.) > > I took the name from Java and only implemented behavior like that, thats wy > I used `final`. > > > >> Ad. 3 it would be awesome if there could be final variables in general, > >> it would be quite stable if no one could change your variable, AFAIK > zvals > >> have IMMUTABLE flag which could be used, don't know it for sure I'm > rather > >> PHP dev than C there would be need some internals guru to ask if it's > >> posiible. > >> > >> P.S. We've meet on PHPCon'15 in Poland, thanks for +1. > >> > > > > YW! > > > > > >> > >> Cheers, > >> -- > >> Michał Brzuchalski (aka brzuchal) > >> > >> 2016-04-05 11:13 GMT+02:00 Marco Pivetta <ocram...@gmail.com>: > >> > >>> Hi Michał, > >>> > >>> First of all: +1 to this: very useful for value objects! > >>> > >>> A few questions: > >>> > >>> * can you re-declare a final property in a sub-class, making it > >>> therefore non-final? (I have reasons to do that, related with altering > >>> states via mappers) > >>> * do we want to use `final`, or `immutable` for these properties? > >>> `final` seems to just be a confusing term here. > >>> * is this feature portable to variables in general? I realize that > >>> adding metadata to ZVals has huge performance implications, but it > would be > >>> interesting to do that for performance improvements further down the > line > >>> > >>> Cheers, > >>> > >>> > >>> Marco Pivetta > >>> > >>> http://twitter.com/Ocramius > >>> > >>> http://ocramius.github.com/ > >>> > >>> On 4 April 2016 at 19:53, Michał Brzuchalski <mic...@brzuchalski.com> > >>> wrote: > >>> > >>>> Hey Internals, > >>>> > >>>> I'm new here. I've been wondering / working on adding final properties > >>>> into > >>>> PHP lang. > >>>> > >>>> This work started once I had the time to read the "Core Java for > >>>> Impateient" by Cay S. Horstmann > >>>> and found it very usefull to have final properties like Java. > >>>> > >>>> Those properties differ than `const` because they can be set at > runtime > >>>> - > >>>> but only once in their lifetime. > >>>> Such properties could be very usefull in Singletons, ValueObjects etc. > >>>> impl > >>>> like: > >>>> > >>>> class Money { > >>>> public final $amount; > >>>> public final $currency; > >>>> public function __constructor($amount, $currency) { > >>>> $this->amount = $amount; > >>>> $this->currency = $currency; > >>>> } > >>>> } > >>>> > >>>> In above example there is even no need for getter because those > >>>> properties > >>>> are immutable through > >>>> the final keyword, it means those properties cannot change their > >>>> references > >>>> just like in Java > >>>> https://en.wikipedia.org/wiki/Final_(Java) > >>>> > >>>> I've already started some impl on own fork > >>>> > >>>> > https://github.com/php/php-src/compare/master...brzuchal:final-properties > >>>> I've got some basics in C programming, don't know yet if I can impl it > >>>> complex. > >>>> > >>>> I was wondering if it is usefull in yours opinion or is it only my > >>>> impression. > >>>> > >>>> I can provide an RFC if it sounds usefull and if I get Wiki karma > >>>> > >>>> Thanks > >>>> -- > >>>> Michał Brzuchalski (aka brzuchal) > >>>> > >>> > >>> > >> > > As an additional question: how will this (eventually) play with typed > > properties? I am aware that you cannot declare a class named `final`, but > > that may change in future, so better factor it into any possible outcomes > > of the RFC. > > > > I don't know if it works with typed properties. > I can provide an RFC but need Wiki Karma (or smth like that) for my account > (login: brzuchal) and don't know how to receive it. > > > > Cheers, > > > > Marco Pivetta > > > > http://twitter.com/Ocramius > > > > http://ocramius.github.com/ > > > > Cheers, > -- > Michał Brzuchalski (aka brzuchal) > I started a discussion on this a while back, but it fizzled due to not having an elegant solution for the 'give me a new one of these with these values changed' problem. I would HIGHLY suggest not using the final keyword. If final is used as a keyword I would expect it to mean that this property definition cannot be changed in a child class. See: https://marc.info/?l=php-internals&m=144766539202647&w=2 Would be happy to pick this up again and help get the RFC created.
