Property Hooks

I do believe this has merit and uses cases, but I agree that value objects would cover this better and there are other things the developers could put their time towards

This RFC needs a re-work. While I support the idea, I don't think this is the right approach. The fact that the RFC is so long is a massive red flag. For example there are 4 different ways to define hooks:

class User
{
    public string $username {
        set(string $value) {
            $this->username = strtolower($value);
        }
    }
}

class User
{
    public string $username {
        set(string $value) {
            $field = strtolower($value);
        }
    }
}

class User
{
    public string $username {
        set => strtolower($value);
    }
}

class User
{
    public function __construct(
        public string $username { set => strtolower($value); }
    ) {}
}

Why?!

This is not what PHP needs.

I enjoy using set/get hooks in C# and strongly believe they are truly useful. Also, having them in interfaces is excellent!

Even if you won't use this yourselve, it will allow libraries and frameworks to do some really cool stuff. LGTM!

I've always envied C# developers for this feature in C#, I've been using __get() and __set() methods to achieve it

It's hard to read.

This RFC does not solve any issue, that cannot be solved right now with almost the same code, and makes the code harder to read. Beside this, this syntax invites developers to mix concerns.

Getters and setters are more and more considered bad : https://www.infoworld.com/article/2073723/why-getter-and-setter-methods-are-evil.html

This features feels like a C# fix applied on PHP which I don't like. We should focus on designing better classes, not fix a bad pattern.

i think it went too far with the virtuals

<?php

class User
 {
    public string $name = 'default'
     {
        set
         {
            if (strlen($value) === 0)
             {
                throw new ValueError("Name must be non-empty");
             }
            $field = ucfirst($value);
         }
        get
         {
            notifyMutationObserver();
            return $this->name;
         }
     }
    public string $badIdeaNoSetterVirdualProp
     {
        get
         {
            return $this->name;
         }
        // set ERROR! I don't like this idea...
     }
    public readonly array $lazy
     {
         get
          {
             return $this->lazy = getBigData();
          }
        // set NO! see declaration, its readonly
      }
    public function __construct(string $name)
     {
        $this->name = $name;
        unset($this->lazy);
     }
 }

$u = new User('roman');
var_dump($u->name);

I prefer the addition of these types of features to the language. Small changes, which in principle will only be used for very specific cases. But in the end they serve to reduce hundreds of lines of superfluous code and make the code easier to read.

Any boilerplate that can go should go

Is a type of writing properties that has also established itself very well in other languages, I would love to see this also in PHP

Simple validation in most cases should be done by passing value object, which already is in valid state.

it is easy to manupulate

i like this just for cutting down the abuse of magic methods. Likewise, if you opt for concrete get/set methods, you add irritating boilerplate, and clutter up functionality. The interface has to be concerned with implementation (i.e. knowing what properties are expected), or API documentation has to be coupled with specific implementation.

i see the constructive points being made against this (more than just "ew it looks like C#"), but i think this feature can coexist with other patterns. There's no magic bullet design pattern, so it's naive to say pattern A always is better than B so B shouldn't exist.

i'm on board with those who dislike the magic variables. Replacing magic __get()/__set() with magic variables is nauseating.

i think this RFC needs to require arrow-functions v2 before it gets reconsidered. Then the hooks can use that syntax with more concrete code:

class Foo {
    public string $bar {
        get: ($field) => {
            // do multi-line stuff
        },
        set: (&$field, $value) => {
            // do multi-line stuff
        }
    };
}

$field is defined and passed with the concrete property's value. For get it's a pass-by-value to avoid magic writes back to the property, and in set it's a reference to confer the new value back to the property. The syntax is required, but you can name the variables whatever makes sense to you (same as you can do with magic method parameters).