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0 pointsNaN13524y ago0 comments

Can you directly cast an object / assoc array to an instance of such a class?

If I have a function that receives eg a Message, it means an instance of the class right? So somehow my assoc.array/object still needs to be instanced, and if I do just $message = new Message($theData) … it doesn’t auto assign properties right? That would be handy though still very much boilerplate.

I guessthe language is just designed for how it’s been used so far, may e it will change if JIT makes php more open ended in its uses.

0 comments

TrispusAttucks4y ago

I never had to do this and I don't believe you can do this directly via a language construct but you can do it within a class via a method or trait or static function. This trait can then be applied to any class. Probably be better though to just have a create function that takes an input of type and coverts to class.

Anyway I was curious so I wanted to try this out with the trait method here is working code that illustrates this.

    <?php

    /* trait to cast from any iterable to class */
    /* reusable - close to what I think you are asking for */
    trait castFrom
    {
        static function castFrom($data)
        {
            if (!is_iterable($data) and !is_array($data) and !is_object($data)) return null;
            $class = new self();
            foreach((array)$data as $key => $value)
            {
                if (!property_exists($class, $key)) continue;
                $class->$key = $value;
            }
            return $class;
        }
    }

    class Foo
    {
        use castFrom; // use the castFrom trait
        public string $str = 'blah';
        public int $num = 5;
        public function hello() { echo "{$this->str} : {$this->num}\n"; }
    }

    class Bar
    {
       use castFrom; // we can use the castFrom trait again and again
       public int $x = 0;
       public int $y = 0;
       public function hello() { echo ($this->x * $this->y) . "\n"; }
    }

    $data = ['str' => 'foo', 'num' => 7, 'x' => 3, 'y' => 7];

    $foo = Foo::castFrom($data);
    $foo->hello();

    print_r($foo);

    $obj = (object)$data;

    $bar = Bar::castFrom($obj);
    $bar->hello();

    print_r($bar);

    /* you could just use create functions form the class */
    class Creator
    {
        static public function createFromArray($data)  {} // create from array
        static public function createFromObject($data) {}   // create from object
        static public function createFromSerial($data) {}   // etc..
        static public function createFromJson($data)   {}
    }

EDIT: Added ugly check to make sure the type can be iterated over.

tyingq4y ago

It's not clear to me what you're looking for. But you can cast arrays to objects. And you can use type declarations as arguments for functions.

AltruisticGapHN4y ago

Ok say I have a small class with an options object (I know perhaps not the best design...):

    class Foo {
      public function __construct(string $name, array $options)
      {
        $this->name = $name;
        if ($options->enableFlag) { ...

I want to declare what $options are, in TS I could do:

type TFooOptions = { enableFlag: boolean; userIds: number[]; }

Then

    function __construct(string $name, TFooOptions $options) ...

Otherwise how do I get proper typechecking if the IDE doesn't know what $options are?

simion3144y ago

>type TFooOptions

is that creating a JS class under the hood or is just a hint for the compiler?

What I do , but I don't work with recent PHP versions is to create this as a class, then to make this easy to construct objects from JSON i add a static function fromObject or fromJson that does it for me. Using real classes could prevent bugs when working with shit APIs like Microsoft TTS , where they have 2 endponts and one returns objects like voice: {name:"Bob"} and the other voice: {Name:"Bob"} so my code will wrap both type of responses into a well defined class.

I don't think there is a PHPDoc annotation just to hint what that object looks like but I will be happey to be shown a way.

1 more reply

bennyp1014y ago

You can get some basic checking, but not type in arrays [1]. Maybe using attributes you could check if it is?

  class TFooOptions
  {
      public function __construct(
          public bool $enableFlag,
          public array $userIds = [],
      ) {
      }
  }

  $options = new TFooOptions(
      enableflags: true,
      userIds: [1,2,3]
  );

  new Foo('Bob', $options);

Or if just for IDE checking, you could use the @property docblock value on the class.

[1] https://wiki.php.net/rfc/arrayof

jorams4y ago

PHP doesn't do such structural typing, but Psalm[1] can do it statically. It calls them object-like arrays.[2]

[1]: https://psalm.dev/ [2]: https://psalm.dev/docs/annotating_code/type_syntax/array_typ...

tyingq4y ago

You can force a type check that it's a specific type of object or interface rather than an array. But, no, you can't do what you're asking for directly.

j / k navigate · click thread line to collapse

0 comments

TrispusAttucks4y ago

Anyway I was curious so I wanted to try this out with the trait method here is working code that illustrates this.

    <?php

    /* trait to cast from any iterable to class */
    /* reusable - close to what I think you are asking for */
    trait castFrom
    {
        static function castFrom($data)
        {
            if (!is_iterable($data) and !is_array($data) and !is_object($data)) return null;
            $class = new self();
            foreach((array)$data as $key => $value)
            {
                if (!property_exists($class, $key)) continue;
                $class->$key = $value;
            }
            return $class;
        }
    }

    class Foo
    {
        use castFrom; // use the castFrom trait
        public string $str = 'blah';
        public int $num = 5;
        public function hello() { echo "{$this->str} : {$this->num}\n"; }
    }

    class Bar
    {
       use castFrom; // we can use the castFrom trait again and again
       public int $x = 0;
       public int $y = 0;
       public function hello() { echo ($this->x * $this->y) . "\n"; }
    }

    $data = ['str' => 'foo', 'num' => 7, 'x' => 3, 'y' => 7];

    $foo = Foo::castFrom($data);
    $foo->hello();

    print_r($foo);

    $obj = (object)$data;

    $bar = Bar::castFrom($obj);
    $bar->hello();

    print_r($bar);

    /* you could just use create functions form the class */
    class Creator
    {
        static public function createFromArray($data)  {} // create from array
        static public function createFromObject($data) {}   // create from object
        static public function createFromSerial($data) {}   // etc..
        static public function createFromJson($data)   {}
    }

EDIT: Added ugly check to make sure the type can be iterated over.

tyingq4y ago

It's not clear to me what you're looking for. But you can cast arrays to objects. And you can use type declarations as arguments for functions.

AltruisticGapHN4y ago

Ok say I have a small class with an options object (I know perhaps not the best design...):

    class Foo {
      public function __construct(string $name, array $options)
      {
        $this->name = $name;
        if ($options->enableFlag) { ...

I want to declare what $options are, in TS I could do:

type TFooOptions = { enableFlag: boolean; userIds: number[]; }

Then

    function __construct(string $name, TFooOptions $options) ...

Otherwise how do I get proper typechecking if the IDE doesn't know what $options are?

simion3144y ago

>type TFooOptions

is that creating a JS class under the hood or is just a hint for the compiler?

I don't think there is a PHPDoc annotation just to hint what that object looks like but I will be happey to be shown a way.

1 more reply

bennyp1014y ago

You can get some basic checking, but not type in arrays [1]. Maybe using attributes you could check if it is?

  class TFooOptions
  {
      public function __construct(
          public bool $enableFlag,
          public array $userIds = [],
      ) {
      }
  }

  $options = new TFooOptions(
      enableflags: true,
      userIds: [1,2,3]
  );

  new Foo('Bob', $options);

Or if just for IDE checking, you could use the @property docblock value on the class.

[1] https://wiki.php.net/rfc/arrayof

jorams4y ago

PHP doesn't do such structural typing, but Psalm[1] can do it statically. It calls them object-like arrays.[2]

[1]: https://psalm.dev/ [2]: https://psalm.dev/docs/annotating_code/type_syntax/array_typ...

tyingq4y ago

You can force a type check that it's a specific type of object or interface rather than an array. But, no, you can't do what you're asking for directly.

j / k navigate · click thread line to collapse