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To: Eugene Sidelnyk <zsidelnik@gmail.com>, Nikita Popov <nikita.ppv@gmail.com>
Cc: PHP Internals <internals@lists.php.net>
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Date: Fri, 16 Jul 2021 12:02:59 +0200
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Subject: Re: [PHP-DEV] Readonly properties - immutability by default
From: pierre-php@processus.org (Pierre)

Le 16/07/2021 à 10:11, Eugene Sidelnyk a écrit :
> Thanks for your response!
> Anyway, I probably put it wrong by saying "by default", so let me clarify
> myself.
>
> What I really mean is omitting the dollar sign. So everything remains the
> same with ordinary properties (which are mutable), and we introduce
> immutable (readonly) properties as another type of them.
> It looks like a great default:
> ```php
>      public string name;
> ```
>
> So, once again, it has nothing to do with backward compatibility. No one
> disposes the way properties are currently working. We introduce a new
> _type_ or _kind_ of properties - readonly.
>
> Also I see useful future scope like readonly parameters:
>
> ```php
> function foo(int firstParam, bool secondParam)
> {
>    // no way to modify it, Error
>    firstParam = 23 * secondParam;
>
>    return firstParam * secondParam;
> }
> ```
>
> Yes, we can implement this with another keyword (again, `readonly`), but as
> I see, only few people will use it because it is too complicated (really,
> instead of simply declaring an argument, a programmer has to write a bunch
> of other stuff in front of it for every single method and function).

Hello,

I'm very happy that the readonly properties RFC did pass, I waited for 
this for a long time.

I like the "readonly" explicit keyword, explicit is always better than 
implicit for disambiguation and readability. I'd wish having per-default 
readonly properties as well, but this is PHP and fundamentals cannot be 
changed just like that, it's not Rust, or any other language, PHP is PHP.

Explicit "readonly" is in my opinion the best option, it's easy to type, 
and it's easy to read, and it's the same keyword in many other 
languages. On the opposite side, omiting the $ sign seems like a huge 
mind-fuck, easy to miss-read, easy to miss-type, error prone and obscure.

Regards,

--

Pierre