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Date: Sat, 14 Sep 2019 01:47:25 -0700
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Cc: =?utf-8?Q?Micha=C5=82_Brzuchalski?= <michal.brzuchalski@gmail.com>,
 PHP Internals List <internals@lists.php.net>
To: Rasmus Schultz <rasmus@mindplay.dk>
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Subject: Re: [PHP-DEV] [RFC] Object Initializer
From: mike@newclarity.net (Mike Schinkel)

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> On Sep 13, 2019, at 3:18 AM, Rasmus Schultz <rasmus@mindplay.dk =
<mailto:rasmus@mindplay.dk>> wrote:
>=20
> Assuming the fields of this entity are required, you would probably =
prefer
> to add a constructor - but then property initializers aren't really =
useful
> anymore.=20

I think this is a false dichotomy; I can see benefit to having =
initializers in addition to constructors, even for the same classes.

However, Object Initializers might be best when paired with a new magic =
method which let us call __init(), and a required modifier for =
properties. =20

Using your Customer example, the __init() would be automatically called =
after __construct():

class Customer
{
   private string $name =3D '';
   required protected ?string $email =3D null;

   public function __construct(string $name, ?string $email =3D null)
   {
      $this->name =3D $name;
      $this->email =3D $email;
    }

   public function __init() =20
   {
      $this->name  =3D ucwords($this->name);
      $this->email =3D sanitize_email($this->email);
   }
}

With __init() a developer could separate capturing construct parameters =
from initializing required fields, but the required modifier would allow =
developers to indicate which properties should be required.=20

And it might even make sense to throw an error if an object initializer =
does not have an __init() method. Requiring __init() would ensure that =
classes not designed to work with initializers would never be =
initialized without required fields set.

When creating an object using object initialization I think it should =
just bypass and only call __init(). PHP could generate an error if any =
required fields are not set.

$customer =3D new Customer{
   name  =3D> 'mike schinkel',
   email =3D> 'mike@newclarity.net <mailto:mike@newclarity.net>'
}
echo $customer->name; // Prints "Mike Schinkel"

Actually, a required modifier would not be required to implement object =
initializers (no pun intended) but it would enable IDEs, PHP and other =
tools validate whether or not a required fields has been set.

As an aside, it would be interesting if there were a __validate() magic =
method although it might harm performance too much.  OTOH, it should not =
harm performance unless you actually use it:

public function __validate(string $field):bool
{
   switch ($field) {
      case 'name':
         return !empty( $this->name ) && strlen($this->name) >=3D 3;
      case 'email':
         return validate_email($this->email);
   }
   return true;
}

> a desire to use this language feature will drive architecture. ... =
this will
> provide the wrong kind of motivation to make what are, effectively,
> architectural decisions.

The reason I badly want object initializers is to empower architectures =
that currently are not possible in PHP. So I see this as a positive.=20

I see architectures used in other languages that reduce tedium and =
enhance reusability that we cannot implement in PHP because of lack of =
an object initializer.

But maybe I do not realize what you are seeing?  Can you please =
elaborate on the architectures you fear will emerge, ideally with =
examples and reasons why they should be avoided?


-Mike


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