Belajar PHP OOP Part 1.20 : Trait (Properties, Function Overriding, Overriding, Visibility Override)

BIKIN BALIK

6 Nov, 2022

Selain class dan interface, di PHP terdapat feature lain bernama trait
Trait mirip dengan abstract class, kita bisa membuat konkrit function atau abstract function
Yang membedakan adalah, di trait bisa kita tambahkan ke dalam class lebih dari satu
Trait mirip seperti ekstension, dimana kita bisa menambahkan konkrti function ke dalam class dengan trait
Secara sederhana trait adalah digunakan untuk menyimpan function-function yang bisa digunakan ulang di beberapa class
Untuk menggunakan trait di class, kita bisa menggunakan kata kunci use

<?php

namespace Data\Traits;

trait SayGoodBye
{
    public string $name;

    public function goodBye (?string $name): void
    {
        if (is_null($name)) {
            echo "Good bye" . PHP_EOL;
        } else {
            echo "Good Bye $name" . PHP_EOL;
        }
    }
}


trait SayHello
{
    public string $name;

    public function hello (?string $name): void
    {
        if (is_null($name)) {
            echo "Hello" . PHP_EOL;
        } else {
            echo "Hello $name" . PHP_EOL;
        }
    }
}

class Person
{
    use SayGoodBye, SayHello;
}

<?php

require_once "data/SayGoodBye.php";

use Data\Traits\{Person, SayHello, sayGoodBye};

$person = new Person();
$person->goodBye("Joko");
$person->hello("Budi");

Trait Properties

Berbeda dengan interface, di trait, kita bisa menambahkan properties
Dengan menambahkan properties, secara otomatis class tersebut akan memiliki properties yang ada di trait

<?php

namespace Data\Traits;

trait SayGoodBye
{
    public string $name;

    public function goodBye (?string $name): void
    {
        if (is_null($name)) {
            echo "Good bye" . PHP_EOL;
        } else {
            echo "Good Bye $name" . PHP_EOL;
        }
    }
}


trait SayHello
{
    public string $name;

    public function hello (?string $name): void
    {
        if (is_null($name)) {
            echo "Hello" . PHP_EOL;
        } else {
            echo "Hello $name" . PHP_EOL;
        }
    }
}

// Trait Menambahkan Properties
trait HashName
{
    public string $name;
}

class Person
{
    use SayGoodBye, SayHello, HashName;
}

<?php

require_once "data/SayGoodBye.php";

use Data\Traits\{Person, SayHello, sayGoodBye};

$person = new Person();
$person->goodBye("Joko");
$person->hello("Budi");

//Trait Menambahkan Properties
$person->name = "Eko";
var_dump($person);

Trait Function Overriding

Selain konkrit function, di trait juga kita bisa menambahkan abstract function
Jika terdapat abstract function di trait, maka secara otomatis function tersebut harus di override di class yang menggunakan trait tersebut

Sebelum function di overriding

<?php

namespace Data\Traits;

trait SayGoodBye
{
    public string $name;

    public function goodBye (?string $name): void
    {
        if (is_null($name)) {
            echo "Good bye" . PHP_EOL;
        } else {
            echo "Good Bye $name" . PHP_EOL;
        }
    }
}


trait SayHello
{
    public string $name;

    public function hello (?string $name): void
    {
        if (is_null($name)) {
            echo "Hello" . PHP_EOL;
        } else {
            echo "Hello $name" . PHP_EOL;
        }
    }
}

trait HashName
{
    public string $name;
}

trait CanRun
{
    public abstract function run(): void;
}

class Person
{
    use SayGoodBye, SayHello, HashName, CanRun;
}

<?php

require_once "data/SayGoodBye.php";

use Data\Traits\{Person, SayHello, sayGoodBye};

$person = new Person();
$person->goodBye("Joko");
$person->hello("Budi");


$person->name = "Eko";
var_dump($person);

Sesudah Function di Overriding

<?php

namespace Data\Traits;

trait SayGoodBye
{
    public string $name;

    public function goodBye (?string $name): void
    {
        if (is_null($name)) {
            echo "Good bye" . PHP_EOL;
        } else {
            echo "Good Bye $name" . PHP_EOL;
        }
    }
}


trait SayHello
{
    public string $name;

    public function hello (?string $name): void
    {
        if (is_null($name)) {
            echo "Hello" . PHP_EOL;
        } else {
            echo "Hello $name" . PHP_EOL;
        }
    }
}

trait HashName
{
    public string $name;
}

trait CanRun
{
    public abstract function run(): void;
}

class Person
{
    use SayGoodBye, SayHello, HashName, CanRun;
    public function run(): void
    {
        echo "Person $this->name is running" . PHP_EOL;
    }
}

<?php

require_once "data/SayGoodBye.php";

use Data\Traits\{Person, SayHello, sayGoodBye};

$person = new Person();
$person->goodBye("Joko");
$person->hello("Budi");


$person->name = "Eko";
var_dump($person);

$person->run();

Trait Overriding

Jika sebuah class memiliki parent class, yang memiliki function yang sama dengan function di trait, maka secara otomatis trait akan meng-override function tersebut
Namun jika kita membuat function yang sama di class nya, maka secara otomatis kita akan meng-override function di trait
Sehingga posisinya seperti ini ParentClass = override by => Trait = override by => ChildClass

Trait => Override by => ChildClass

<?php

namespace Data\Traits;

trait SayGoodBye
{
    public string $name;

    public function goodBye (?string $name): void
    {
        if (is_null($name)) {
            echo "Good bye" . PHP_EOL;
        } else {
            echo "Good Bye $name" . PHP_EOL;
        }
    }
}

trait SayHello
{
    public string $name;

    public function hello (?string $name): void
    {
        if (is_null($name)) {
            echo "Hello" . PHP_EOL;
        } else {
            echo "Hello $name" . PHP_EOL;
        }
    }
}

trait HashName
{
    public string $name;
}

trait CanRun
{
    public abstract function run(): void;
}

class Person
{
    use SayGoodBye, SayHello, HashName, CanRun;
    public function run(): void
    {
        echo "Person $this->name is running" . PHP_EOL;
    }

    public function goodBye(?string $name): void
    {
        echo "Good by in Person" . PHP_EOL;
    }

    public function hello(?string $name): void
    {
        echo "Good bye in Person" . PHP_EOL;
    }
}

<?php

require_once "data/SayGoodBye.php";

use Data\Traits\{Person, SayHello, sayGoodBye};

$person = new Person();
$person->goodBye("Joko");
$person->hello("Budi");


$person->name = "Eko";
var_dump($person);

$person->run();

Parent Class => Override by => Trait

<?php

namespace Data\Traits;

trait SayGoodBye
{
    public string $name;

    public function goodBye (?string $name): void
    {
        if (is_null($name)) {
            echo "Good bye" . PHP_EOL;
        } else {
            echo "Good Bye $name" . PHP_EOL;
        }
    }
}

trait SayHello
{
    public string $name;

    public function hello (?string $name): void
    {
        if (is_null($name)) {
            echo "Hello" . PHP_EOL;
        } else {
            echo "Hello $name" . PHP_EOL;
        }
    }
}

trait HashName
{
    public string $name;
}

trait CanRun
{
    public abstract function run(): void;
}

class ParentPerson
{
    public function goodBye(?string $name): void
    {
        echo "Good by in Person" . PHP_EOL;
    }

    public function hello(?string $name): void
    {
        echo "Good bye in Person" . PHP_EOL;
    }
}

class Person extends ParentPerson
{
    use SayGoodBye, SayHello, HashName, CanRun;
    public function run(): void
    {
        echo "Person $this->name is running" . PHP_EOL;
    }

}

<?php

require_once "data/SayGoodBye.php";

use Data\Traits\{Person, SayHello, sayGoodBye};

$person = new Person();
$person->goodBye("Joko");
$person->hello("Budi");


$person->name = "Eko";
var_dump($person);

$person->run();

Trait Visibility Override

Selain melakukan override function di class, kita juga bisa melakukan override visibility function yang terdapat di trait
Namun untuk melakukan ini tidak perlu membuat function baru di class, kita bisa gunakan secara sederhana ketika mengunakan trait nya

<?php

namespace Data\Traits;

trait SayGoodBye
{
    public string $name;

    public function goodBye (?string $name): void
    {
        if (is_null($name)) {
            echo "Good bye" . PHP_EOL;
        } else {
            echo "Good Bye $name" . PHP_EOL;
        }
    }
}

trait SayHello
{
    public string $name;

    public function hello (?string $name): void
    {
        if (is_null($name)) {
            echo "Hello" . PHP_EOL;
        } else {
            echo "Hello $name" . PHP_EOL;
        }
    }
}

trait HashName
{
    public string $name;
}

trait CanRun
{
    public abstract function run(): void;
}

class ParentPerson
{
    public function goodBye(?string $name): void
    {
        echo "Good by in Person" . PHP_EOL;
    }

    public function hello(?string $name): void
    {
        echo "Good bye in Person" . PHP_EOL;
    }
}

class Person extends ParentPerson
{
    use SayGoodBye, SayHello, HashName, CanRun{
        hello as private;
        goodBye as private;
    }

    public function run(): void
    {
        echo "Person $this->name is running" . PHP_EOL;
    }

}

<?php

require_once "data/SayGoodBye.php";

use Data\Traits\{Person, SayHello, sayGoodBye};

$person = new Person();
$person->goodBye("Joko");
$person->hello("Budi");


$person->name = "Eko";
var_dump($person);

$person->run();

Trait Properties

Trait Function Overriding

Sebelum function di overriding

Sesudah Function di Overriding

Trait Overriding

Parent Class => Override by => Trait

Trait Visibility Override

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