The old (Pierrick) version of the enum RFC can be found at https://wiki.php.net/rfc/enum?rev=1302087566

• Version: 1.0
• Date: 2010-05-21
• Author: Pierrick Charron pierrick@php.net
• Status: Under Discussion
• First Published at: http://wiki.php.net/rfc/enum

This RFC is about adding the enum language structure.

When writing a program, it is often required to create lists of constants representing integers to make the code more readable. This RFC introduce a new language construct to define such a list by assigning unique arbitrary values or not.

Frequently developers need to produce code like this:

const	LOG_LEVEL_DEBUG = 1,
	LOG_LEVEL_INFO = 2,
	LOG_LEVEL_WARNING = 3,
	LOG_LEVEL_ERROR = 4;
 
// Or
 
class Tokens {
	const	T_IF = 258,
		T_ELSE = 259,
		T_WHILE = 260,
		T_DO = 261;
}

The proposal is that this could be written in a much more concise manner:

enum { 
	LOG_LEVEL_DEBUG,
	LOG_LEVEL_INFO,
	LOG_LEVEL_WARNING,
	LOG_LEVEL_ERROR 
};
 
// Or
 
class Tokens {
	enum { 
		T_IF = 258,
		T_ELSE,
		T_WHILE,
		T_DO 
	};
}

namespace Cards;
 
enum Suit {
	SPADES => 1,
	HEARTS => 2,
	DIAMONDS, // Will have value 3
	CLUBS,    // Will have value 4
}
 
var_dump( Suit::SPADES );         // enum(Cards\Suit)(1)
var_dump( Suit::SPADES == 1 );    // bool(true)
var_dump( Suit::SPADES === 1 );   // bool(true)
var_dump( Suit::SPADES == '1' );  // bool(true)
var_dump( Suit::SPADES === '1' ); // bool( false )

The keyword enum is reserved. An enum may be defined wherever a class or interface could be defined, and the same namespacing, naming and referencing restrictions apply.

• Requiring the existing const keyword before the enum; this largely eliminates B/C issues.