Access Class Constants Dynamically in PHP

Question

I want to be able to look up the value of a constant dynamically, but using a variable doesn't work with the syntax.

<?php
class Food {
    const FRUITS = 'apple, banana, orange';
    const VEGETABLES = 'spinach, carrot, celery';
}

$type = 'FRUITS';

echo Food::FRUITS;
echo Food::$type;

?>

gives

apple, banana, orange

Fatal error: Access to undeclared static property: Food::$type

How can I dynamically call the constant?

Answer 1

The only solution which comes to my head is using a constant function:

echo constant('Food::' . $type);

Here you create name of a constant, including class, as a string and pass this string ('Food::FRUITS') to constant function.

Answer 2

This will be available natively in php8.3 as of November 2023

class MyClass {
    public const MY_CONST = 42;
}

$constName = 'MY_CONST';

echo MyClass::{$constName};

https://php.watch/versions/8.3/dynamic-class-const-enum-member-syntax-support