PHP/enum

PHP enum support

Examples

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

Methods

kind of thing	name & args	returns	defined in	description
static function	cases()	array	UnitEnum	returns a packed array of all defined cases, in order of declaration
static function	tryFrom(int|string $value)	?static	BackedEnum	same as from(), but returns NULL if not found (instead of erroring)
static function	from(int|string $value)	static	BackedEnum	same as tryFrom, but throws an error if not found
dynamic property	$name	string	UnitEnum	the name of the case (case-sensitive)
dynamic property	$value	int or string	BackedEnum	the value of the case

Caveats

Enums are similar to objects in that:

• An enum case will pass the is_object() test. (I think.)
• They may implement interfaces.
• Code in their methods may use self:: and $this->.
• The ::class magic constant works.

Enums are different from objects in that:

• They cannot be extended, or extend other entities.
• They can't have constructors or destructors.
• They can't have static properties.
• The ::class magic constant exists on individual cases (enum instances) as well.
• An enum can't be instantiated like an object; individual cases are similar to singleton objects.
  • Cases also provide the ::class magic constant. (I don't think this works on regular objects.)

Not sure if enum cases can be used as switch cases (to be checked).

Documentation

Note that enums can be cast directly to arrays.

• Enumerations:
  • variable type
  • Enumerations language reference
    • "Basic" enums
    • "Backed" enums
• Demiclasses:
  • UnitEnum
  • BackedEnum

3rd party

• stitcher.io

Sample Code

To get a UnitEnum enum from a case name (equivalent to from()/tryFrom()):

• constant("<enum name>::{$value}")

Tests

• is an enum case an object (is_object)? [YES]
• is an enum seen as is_a UnitEnum? [YES]
• is an enum an instanceof UnitEnum? [YES]
• is an enum an instanceof enum? [no]