Re: Readonly properties - immutability by default

On Fri, Jul 16, 2021 at 8:45 AM Eugene Sidelnyk <zsidelnik@gmail.com> wrote: > This is replica of github PR comments: > > Hi there! > Isn't it better to simplify this a bit? I mean readonly > keyword is really > long to type every time we need such property. Earlier (in php7.3) > properties were defined only with visibility modifier. Now it is going to > become *toooo verbose*. > > ```php > class A > { > // 24 characters before actual property name > readonly public string $name; > readonly public string $another; > > public function __construct(string $var) > { > $this->name = $var; > $this->another = $var; > } > } > > $a = new A('foo'); > var_dump($a); > ``` > > What seems for me to be better is remove readonly modifier at > all, with > somewhat different modification. Look at the code below. This is intended > to work the same way as previous example. > > ```php > class A > { > // 14 characters before actual property name > public string name; > public string another; > > public function __construct(string $var) > { > $this->name = $var; > $this->another = $var; > } > } > > $a = new A('foo'); > var_dump($a); > ``` > > This is less explicit (we don't actually write readonly > keyword), and it > may be confusing for some programmer who is new to php. However after first > attempt of modification, such layman will understand it's syntax and keep > with it. > > Readonly properties are really useful for DDD, where everything is going to > be immutable. It promotes best practices. However for people to use it, > syntax should be concise and brief. > > @nikic , want to hear your thoughts on this. > > * kolardavid <https://github.com/kolardavid> * 1 hour ago > > <https://github.com/php/php-src/pull/7089#issuecomment-881191365> > > @rela589n <https://github.com/rela589n> First of all, you > are coming late > (as me before), since this RFC is already voted and implemented completely. > Anyway, I find your suggestion bad. The truth is, that it is a bit more > verbose, but I am OK with that. It might be annoying to write (word > protected is even longer) but it is far better to read. It makes the code > more clear. Human brain is very well "optimized" to notice words it is used > to, more than symbols. This idea stays behind the fact that Delphi for > example uses begin/end instead of { and } (even though I am kind of tired > of it as well). Anyway, your solution of dropping $ for readonly property > would be nightmare for everyone, not just beginners. I am sure that @nikic > <https://github.com/nikic> will say the same, since he > seems as pedantic > as > I am about these things. Since all modifiers are already nice > self-explaining word, there is no point in doing this differently for new > modifier. It wouldn't be consistent, nor convenient. Mixed properties with > and without $ sign would look like typo, not intention. > > * rela589n <https://github.com/rela589n> * 26 minutes ago > > <https://github.com/php/php-src/pull/7089#issuecomment-881206048> > The philosophy of the Functional Programming < > http://en.wikipedia.org/wiki/Functional_programming> > paradigm is strongly > geared towards all "variables" being immutable, and "mutable" ones being > only allowed in extreme cases (ie, for I/O. This will not look like a typo. > Immutability should be provided by default. BTW, in future scope we can > create "readonly" variables. So that once a variable is defined, no one can > change its value. I oppose creating kind of let and > const for this. > > * rela589n <https://github.com/rela589n> * 21 minutes ago > > <https://github.com/php/php-src/pull/7089#issuecomment-881208237> > > Anyway, your solution of dropping $ for readonly property would be > nightmare for everyone, not just beginners > > It would be a nightmare if these values could be changed. As we can't > rewrite readonly property, it looks like a constant. This > concept of > readonly properties should come along with constants not only by semantics, > but also by syntax. > > * rela589n <https://github.com/rela589n> * 18 minutes ago > > <https://github.com/php/php-src/pull/7089#issuecomment-881209502> > > The truth is, that it is a bit more verbose, but I am OK with that. It > might be annoying to write (word protected is even longer) but it is far > better to read. > > We already have Java with it's verbose syntax. We should think what should > be default and safe behaviour covering most cases and make such verbose > constructions for cases not covered by default logic. > We cannot make properties readonly by default, because that would be a major backwards compatibility break. If you're going for brevity, something you can do is omit the visibility specifier, as it is public by default. "readonly int $prop" works. Regards, Nikita