<?php

class Enum
{
    protected $self=array();
    public function _construct()
    {
        $args=func_get_args();
        for($i=0,$n=count($args);$i<$n;$i++)
            $this->add($args[$i]);
    }
    public function _get($name=null)
    {
        return $this->self[$name];
    }
    public function add($name=null,$enum=null)
    {
        if(isset($enum)) $this->self[$name]=$enum;
        else $this->sef[$name]=end($this->self)+1;
    }
}

class DefinedEnum extends Enum
{
    public function _construct($itms)
    {
        foreach($itms as $name=>$enum)
        $this->add($name,$enum);
    }
}

class FlagsEnum extends Enum
{
    public function _construct()
    {
        $args=func_get_args();
        for($i=0,$n=count($args),$f=0x1;$i<$n;$i++,$f*=0x2)
        $this->add($args[i],$f);
    }
}

$eFruits=new Enum("APPLE","ORANGE","PEACH");
echo $eFruits->APPLE.",";
echo $eFruits->ORANGE.",";
echo $eFruits->PEACH."\n";

$eBeers=new DefinedEnum("GUINESS"=>25,"MIRROR_POND"=>49);
echo $eBeers->GUINESS.",";
echo $eBeers->MIRROR_POND."\n";

$eFlags=new FlagsEnum("HAS_ADMIN","HAS_SUPER","HAS_POWER","HAS_GUEST");
echo $eFlags->HAS_ADMIN.",";
echo $eFlags->HAS_SUPER.",";
echo $eFlags->HAS_POWER.",";
echo $eFlags->HAS_GUEST."\n";
?>

 class Enum
{
    protected $self=array();
    public function __construct()
    {
        $args=func_get_args();
        for($i=0,$n=count($args);$i<$n;$i++)
            $this->add($args[$i]);
    }
    public function __get($name=null)
    {
        return $this->self[$name];
    }
    public function add($name=null,$enum=null)
    {
        if(isset($enum)){
            $this->self[$name]=$enum;
        }else{ 
                  $this->self[$name]=end($this->self)+1;
        }        
    }
}

class DefinedEnum extends Enum
{
    public function __construct($itms)
    {
        foreach($itms as $name=>$enum)
        $this->add($name,$enum);
    }
}

class FlagsEnum extends Enum
{
    public function __construct()
    {
        $args=func_get_args();
        for($i=0,$n=count($args),$f=0x1;$i<$n;$i++,$f*=0x2){
            
             $this->add($args[$i],$f);
        }
    }
}

 $eFruits=new Enum("APPLE","ORANGE","PEACH");
echo $eFruits->APPLE.",";
echo $eFruits->ORANGE.",";
echo $eFruits->PEACH."\n";

$eBeers=new DefinedEnum(array("GUINESS"=>25,"MIRROR_POND"=>49));
echo $eBeers->GUINESS.",";
echo $eBeers->MIRROR_POND."\n"; 

$eFlags=new FlagsEnum("HAS_ADMIN","HAS_SUPER","HAS_POWER","HAS_GUEST");
echo ($eFlags->HAS_ADMIN).",";
echo ($eFlags->HAS_SUPER).",";
echo $eFlags->HAS_POWER.",";
echo $eFlags->HAS_GUEST."\n";

------解决方案--------------------
两个下划线就都对了。