New Features in PHP 8: Constructor Property Promotion and Reducing Redundant Code

PHP 8, released on November 26 2020, introduces many exciting features for web development, including constructor property promotion and tools that reduce repetitive code. This article demonstrates how to use these features with examples.

1. Constructor Property Promotion

In earlier PHP versions, developers had to manually define getter and setter methods for class properties. PHP 8 allows the use of constructor property promotion to simplify this process.

Consider the following example where a Person class defines name and age properties with explicit getters and setters:

<code>class Person {
    public string $name;
    public int $age;

    public function getName(): string {
        return $this->name;
    }

    public function setName(string $name): void {
        $this->name = $name;
    }

    public function getAge(): int {
        return $this->age;
    }

    public function setAge(int $age): void {
        $this->age = $age;
    }
}
</code>

With constructor property promotion, the same class can be written more concisely:

<code>class Person {
    public function __construct(
        public string $name,
        public int $age,
    ) {}
}
</code>

Now the getter and setter methods are unnecessary, and the properties can be accessed directly:

<code>$person = new Person('John Doe', 25);
echo $person->name; // outputs: John Doe
echo $person->age;  // outputs: 25
</code>

This demonstrates how property promotion greatly simplifies code structure and eliminates redundancy.

2. Reducing Redundant Code

PHP 8 also adds features that help reduce code duplication, such as named arguments and the null coalescing operator.

Named Arguments

Named arguments allow function calls to specify parameter names, improving readability and flexibility.

Example of a simple sum function:

<code>function sum(int $a, int $b): int {
    return $a + $b;
}
echo sum(5, 10); // outputs: 15
</code>

Using named arguments, the same call can be written as:

<code>echo sum(b: 5, a: 10); // outputs: 15
</code>

This lets developers pass arguments in any order.

Null Coalescing Operator

Previously, checking for null and providing a default required ternary operators or if statements.

Traditional approach:

<code>$username = isset($_GET['username']) ? $_GET['username'] : 'Guest';
</code>

PHP 8 simplifies this with the null coalescing operator ( ?? ):

<code>$username = $_GET['username'] ?? 'Guest';
</code>

Additional new features in PHP 8 include the match expression and static return type declarations, further enhancing the language's capabilities.

Conclusion

The article covered two major PHP 8 features: constructor property promotion, which makes class definitions more concise by removing the need for explicit getters and setters, and tools like named arguments and the null coalescing operator that improve code readability and reduce duplication.