PHP Enumerations

How often have you regretted that PHP has no enums per se?

Yes, someone got along with the naming convention and it turned out something like:

  define ('COLOR_RED', 'F00');
 define ('COLOR_GREEN', '0F0');
 define ('COLOR_BLUE', '00F');

Or something like:

  // this variable is FORBIDDEN to modify
 $ colors = array (
     'red' => 'F00',
     'green' => '0F0',
     'blue' => '00F',
 );

But both approaches have significant drawbacks:

• In the first case, the enumeration members do not form an explicit grouping.
• In the second case, there is a risk that the variable will be changed.
• And in both these cases, we cannot do a check on the type of the variable (type hinting)

Under the cut offer a solution without the above disadvantages ...

 abstract class Enum {
     private $ current_val;
    
     final public function __construct ($ type) {
         $ class_name = get_class ($ this);
        
         $ type = strtoupper ($ type);
         if (constant ("{$ class_name} :: {$ type}") === NULL) {
             throw new Enum_Exception ('Properties'. $ type. 'in the enumeration'. $ class_name. 'not found.'); 
         }
        
         $ this-> current_val = constant ("{$ class_name} :: {$ type}");
     }
    
     final public function __toString () {
         return $ this-> current_val;
     }
 }

 class Enum_Exception extends Exception {}

This is the base class for enums. When working, we will only need to connect it and in the future we can forget about it.
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Well, in order to implement the enumerations themselves, we need to write a similar structure:

 class Enum_Colors extends Enum {
     const RED = 'F00';
     const GREEN = '0F0';
     const BLUE = '00F';
 }

And now to refer to a constant value and use type hinting we need to create an object from this class, passing the name of the necessary constant to the constructor:

 function setColor (Enum_Colors $ color) {
     echo $ color;
 }
 setColor (new Enum_Colors ('GREEN'));  // will pass
 setColor ('0F0');  // won't pass

 Enum_Colors :: RED == new Enum_Colors ('GREEN');  // FALSE

 Enum_Colors :: RED == new Enum_Colors ('RED');  // TRUE

ZY But when PHP5.3 release comes out, you can add a method to the Enum class:
public static method asArray() {}

which will return all pairs: key-value
_original