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Date: Tue, 16 May 2023 00:50:09 +0700
Message-ID: <CAG4FTXzycaguvBOQLf0JZtQnwC83WFFc-mdqK9aucGESGsExBg@mail.gmail.com>
To: Larry Garfield <larry@garfieldtech.com>
Cc: php internals <internals@lists.php.net>
Content-Type: text/plain; charset="UTF-8"
Subject: Re: [PHP-DEV] [RFC] Property hooks, nee accessors
From: the.liquid.metal@gmail.com (Hendra Gunawan)

> If there is no forward compatibility consideration, can we simplify
> interface definition to this one?
> ```
> interface IFace
> {
>   public string $readable;
>   public string $writeable;
>   public string $both;
> }
> ```

After carefully reading the proposal again, I think I know the answer
for my own question.

Short answer: no, we still need ```{ get; }``` to enforce the implemented class.

There are two different things here:
1. enforcing the implemented class
2. enforcing the caller site

If there are only ordinary properties, then ```{ get; }``` is truly
useless at the moment. On the other hand, virtual properties need
rules to be enforced, since there is no default hook given to it.

Since PHP lacks method definition enforcement at the caller site, I
assume that property would suffer the same.

Since we don't know what type of property is in the caller site,
static analysis tools can benefit from ```{ get; }``` to produce a
warning that we should not assign value to the property. A more
complex check should be performed to the implemented class because the
property type can be determined directly (if i am not wrong).
```
interface IFace
{
  public string $readable1 { get; }
  public string $readable2 { get; }
}

class CX implements IFace {
  private string $_propx;

  public string $readable1;
  public string $readable2 {
    get => $this->_propx;
    set => $this->_propx = $value;
  }

  public function consumeIt(IFace $par) {
    // these statements should trigger warning by SA tools
    $par->readable1 = "hello";
    $par->readable2 = "world";

    // OK
    $this->readable1 = "hello";

    // this statement should trigger error by SA tools
    $this->readable2 = "hello";
  }
}
```