Constructor Promotion

Constructor property promotion creates and initializes a property in one place.

constructor_promotion.php

<?php
class Course
{
    public function __construct(private string $title, private int $lessons)
    {
    }

    public function summary(): string
    {
        return $this->title . ":" . $this->lessons;
    }
}

$lessons = ;
$summary = (new Course("PHP", $lessons))->summary();

echo "lessons=" . $lessons . "\n";
echo "summary=" . $summary . "\n";

<?php
class Course
{
    public function __construct(private string $title, private int $lessons)
    {
    }

    public function summary(): string
    {
        return $this->title . ":" . $this->lessons;
    }
}

$lessons = ;
$summary = (new Course("PHP", $lessons))->summary();

echo "lessons=" . $lessons . "\n";
echo "summary=" . $summary . "\n";

<?php
class Course
{
    public function __construct(private string $title, private int $lessons)
    {
    }

    public function summary(): string
    {
        return $this->title . ":" . $this->lessons;
    }
}

$lessons = ;
$summary = (new Course("PHP", $lessons))->summary();

echo "lessons=" . $lessons . "\n";
echo "summary=" . $summary . "\n";

compact initialization Promoted constructor properties reduce repeated boilerplate for simple value objects.