International PHP Conference Berlin 2023

Enumeration static methods

Enumerations may also have static methods. The use for static methods on the enumeration itself is primarily for alternative constructors. E.g.:

<?php
enum Size
{
    case 
Small;
    case 
Medium;
    case 
Large;

    public static function 
fromLength(int $cm): static
    {
        return 
match(true) {
            
$cm 50 => static::Small,
            
$cm 100 => static::Medium,
            default => static::
Large,
        };
    }
}
?>

Static methods may be public, private, or protected, although in practice private and protected are equivalent as inheritance is not allowed.

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User Contributed Notes 2 notes

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33
niloofarfs
9 months ago
To get all scalar equivalents values of Backed Enum as an array you could define a method in your Enum:

<?php

enum Suit
: string
{
    case
Hearts = 'H';
    case
Diamonds = 'D';
    case
Clubs = 'C';
    case
Spades = 'S';

    public static function
values(): array
    {
       return
array_column(self::cases(), 'value');
    }
}

?>
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0
Aaron Saray
28 days ago
Need to retrieve all the names and values immediately from a backed enum (for something like a select box) and you don't want to loop over `Enum::cases()`?  Try this:

<?php
enum Suit
: string
{
    case
Hearts = 'H';
    case
Diamonds = 'D';
    case
Clubs = 'C';
    case
Spades = 'S';

    public static function
forSelect(): array
    {
      return
array_combine(
       
array_column(self::cases(), 'value'),
       
array_column(self::cases(), 'name')
      );
    }
}

Suit::forSelect();
?>

Put `forSelect()` in a trait and use it in any enum you have that needs this functionality.
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