How do constructor property promotion, introduced in PHP 8, reduce boilerplate code when defining a class with several properties initialized directly through its constructor?

Intermediate

Answer

Constructor property promotion lets you declare and initialize a class property directly within the constructor's parameter list, simply by adding a visibility modifier before the parameter, eliminating the previously required boilerplate of separately declaring each property, adding a matching constructor parameter, and manually assigning that parameter's value to the corresponding property inside the constructor body.

class Point {
    public function __construct(
        public readonly float $x,
        public readonly float $y
    ) {}
}

Real-world example A developer refactors a data class that previously required a dozen lines of repetitive property declarations and constructor assignment code down to just a few concise lines using constructor property promotion, significantly improving readability.

Common follow-ups: Can constructor property promotion be combined with the readonly modifier?;Is there any functional difference between a promoted property and a traditionally declared one?

OOP;Type Declarations & Strict Types

All 7 PHP 8 Features (Attributes, Enums, Match, Nullsafe Operator) questions