对于简单的枚举，我使用如下结构。通常，您可以将它们用于switch语句。

<?php 
  define("OPTION_1", "1");
  define("OPTION_2", OPTION_1 + 1);
  define("OPTION_3", OPTION_2 + 1);

  // Some function...
   switch($Val){
    case OPTION_1:{ Perform_1();}break;
    case OPTION_2:{ Perform_2();}break;
    ...
  }
?>

它不像c++中的本地枚举那样方便，但如果你以后想在两者之间添加一个选项，它似乎可以工作，并且需要更少的维护。

我知道这是一个非常非常非常古老的话题，但我对此有一个想法，想知道人们是怎么想的。

注:我在玩这个，并意识到如果我只是修改__call()函数，你可以更接近实际的枚举。__call()函数处理所有未知函数调用。假设你想创建三个枚举RED_LIGHT, YELLOW_LIGHT和GREEN_LIGHT。你现在只需做以下事情就可以做到:

$c->RED_LIGHT();
$c->YELLOW_LIGHT();
$c->GREEN_LIGHT();

一旦定义了，你所要做的就是再次调用它们来获取值:

echo $c->RED_LIGHT();
echo $c->YELLOW_LIGHT();
echo $c->GREEN_LIGHT();

得到0 1 2。玩得开心!这个现在也在GitHub上。

更新:我已经这样做了，所以__get()和__set()函数现在都被使用。这允许您不必调用函数，除非您愿意。相反，现在你可以说:

$c->RED_LIGHT;
$c->YELLOW_LIGHT;
$c->GREEN_LIGHT;

对于价值的创造和获取。因为变量最初还没有定义，所以调用__get()函数(因为没有指定值)，它会发现数组中的条目还没有创建。因此，它创建条目，将最后一个给定值赋给它+1(+1)，对最后一个值变量加1，并返回TRUE。如果你设置这个值:

$c->RED_LIGHT = 85;

然后调用__set()函数，最后一个值被设置为新值+1(+1)。现在我们有了一个很好的方法来处理枚举，并且可以动态地创建它们。

<?php
################################################################################
#   Class ENUMS
#
#       Original code by Mark Manning.
#       Copyrighted (c) 2015 by Mark Manning.
#       All rights reserved.
#
#       This set of code is hereby placed into the free software universe
#       via the GNU greater license thus placing it under the Copyleft
#       rules and regulations with the following modifications:
#
#       1. You may use this work in any other work.  Commercial or otherwise.
#       2. You may make as much money as you can with it.
#       3. You owe me nothing except to give me a small blurb somewhere in
#           your program or maybe have pity on me and donate a dollar to
#           sim_sales@paypal.com.  :-)
#
#   Blurb:
#
#       PHP Class Enums by Mark Manning (markem-AT-sim1-DOT-us).
#       Used with permission.
#
#   Notes:
#
#       VIM formatting.  Set tabs to four(4) spaces.
#
################################################################################
class enums
{
    private $enums;
    private $clear_flag;
    private $last_value;

################################################################################
#   __construct(). Construction function.  Optionally pass in your enums.
################################################################################
function __construct()
{
    $this->enums = array();
    $this->clear_flag = false;
    $this->last_value = 0;

    if( func_num_args() > 0 ){
        return $this->put( func_get_args() );
        }

    return true;
}
################################################################################
#   put(). Insert one or more enums.
################################################################################
function put()
{
    $args = func_get_args();
#
#   Did they send us an array of enums?
#   Ex: $c->put( array( "a"=>0, "b"=>1,...) );
#   OR  $c->put( array( "a", "b", "c",... ) );
#
    if( is_array($args[0]) ){
#
#   Add them all in
#
        foreach( $args[0] as $k=>$v ){
#
#   Don't let them change it once it is set.
#   Remove the IF statement if you want to be able to modify the enums.
#
            if( !isset($this->enums[$k]) ){
#
#   If they sent an array of enums like this: "a","b","c",... then we have to
#   change that to be "A"=>#. Where "#" is the current count of the enums.
#
                if( is_numeric($k) ){
                    $this->enums[$v] = $this->last_value++;
                    }
#
#   Else - they sent "a"=>"A", "b"=>"B", "c"=>"C"...
#
                    else {
                        $this->last_value = $v + 1;
                        $this->enums[$k] = $v;
                        }
                }
            }
        }
#
#   Nope!  Did they just sent us one enum?
#
        else {
#
#   Is this just a default declaration?
#   Ex: $c->put( "a" );
#
            if( count($args) < 2 ){
#
#   Again - remove the IF statement if you want to be able to change the enums.
#
                if( !isset($this->enums[$args[0]]) ){
                    $this->enums[$args[0]] = $this->last_value++;
                    }
#
#   No - they sent us a regular enum
#   Ex: $c->put( "a", "This is the first enum" );
#
                    else {
#
#   Again - remove the IF statement if you want to be able to change the enums.
#
                        if( !isset($this->enums[$args[0]]) ){
                            $this->last_value = $args[1] + 1;
                            $this->enums[$args[0]] = $args[1];
                            }
                        }
                }
            }

    return true;
}
################################################################################
#   get(). Get one or more enums.
################################################################################
function get()
{
    $num = func_num_args();
    $args = func_get_args();
#
#   Is this an array of enums request? (ie: $c->get(array("a","b","c"...)) )
#
    if( is_array($args[0]) ){
        $ary = array();
        foreach( $args[0] as $k=>$v ){
            $ary[$v] = $this->enums[$v];
            }

        return $ary;
        }
#
#   Is it just ONE enum they want? (ie: $c->get("a") )
#
        else if( ($num > 0) && ($num < 2) ){
            return $this->enums[$args[0]];
            }
#
#   Is it a list of enums they want? (ie: $c->get( "a", "b", "c"...) )
#
        else if( $num > 1 ){
            $ary = array();
            foreach( $args as $k=>$v ){
                $ary[$v] = $this->enums[$v];
                }

            return $ary;
            }
#
#   They either sent something funky or nothing at all.
#
    return false;
}
################################################################################
#   clear(). Clear out the enum array.
#       Optional.  Set the flag in the __construct function.
#       After all, ENUMS are supposed to be constant.
################################################################################
function clear()
{
    if( $clear_flag ){
        unset( $this->enums );
        $this->enums = array();
        }

    return true;
}
################################################################################
#   __call().  In case someone tries to blow up the class.
################################################################################
function __call( $name, $arguments )
{
    if( isset($this->enums[$name]) ){ return $this->enums[$name]; }
        else if( !isset($this->enums[$name]) && (count($arguments) > 0) ){
            $this->last_value = $arguments[0] + 1;
            $this->enums[$name] = $arguments[0];
            return true;
            }
        else if( !isset($this->enums[$name]) && (count($arguments) < 1) ){
            $this->enums[$name] = $this->last_value++;
            return true;
            }

    return false;
}
################################################################################
#   __get(). Gets the value.
################################################################################
function __get($name)
{
    if( isset($this->enums[$name]) ){ return $this->enums[$name]; }
        else if( !isset($this->enums[$name]) ){
            $this->enums[$name] = $this->last_value++;
            return true;
            }

    return false;
}
################################################################################
#   __set().  Sets the value.
################################################################################
function __set( $name, $value=null )
{
    if( isset($this->enums[$name]) ){ return false; }
        else if( !isset($this->enums[$name]) && !is_null($value) ){
            $this->last_value = $value + 1;
            $this->enums[$name] = $value;
            return true;
            }
        else if( !isset($this->enums[$name]) && is_null($value) ){
            $this->enums[$name] = $this->last_value++;
            return true;
            }

    return false;
}
################################################################################
#   __destruct().  Deconstruct the class.  Remove the list of enums.
################################################################################
function __destruct()
{
    unset( $this->enums );
    $this->enums = null;

    return true;
}

}
#
#   Test code
#
#   $c = new enums();
#   $c->RED_LIGHT(85);
#   $c->YELLOW_LIGHT = 23;
#   $c->GREEN_LIGHT;
#
#   echo $c->RED_LIGHT . "\n";
#   echo $c->YELLOW_LIGHT . "\n";
#   echo $c->GREEN_LIGHT . "\n";

?>

上面的答案太棒了。但是，如果以两种不同的方式进行扩展，那么无论先进行哪种扩展，都会导致对函数的调用，从而创建缓存。这个缓存将被所有后续调用使用，无论调用是由哪个扩展发起的…

要解决这个问题，将变量和第一个函数替换为:

private static $constCacheArray = null;

private static function getConstants() {
    if (self::$constCacheArray === null) self::$constCacheArray = array();

    $calledClass = get_called_class();
    if (!array_key_exists($calledClass, self::$constCacheArray)) {
        $reflect = new \ReflectionClass($calledClass);
        self::$constCacheArray[$calledClass] = $reflect->getConstants();
    }

    return self::$constCacheArray[$calledClass];
}

我只是创建了一个库，希望它能完成这项工作。它可以在任何PHP项目中独立使用，并且有一些Laravel的好东西可以让生活变得更简单。我在生产项目中使用它们。

https://github.com/Kwaadpepper/enum

如果你喜欢或不喜欢，不要犹豫提供反馈。 它可以被打印出来，并序列化为JSON。它的定义很简单。

用法非常简单:

$enum = BasicEnum::someValue();
echo $enum->equals(BasicEnum::someValue()) ? 'true' : 'false'; // true
echo $enum->value; // 'someValue' or the value you have defined
echo $enum->label; // 'someValue' or the label you have defined
echo $enum; // 'someValue' or the value you have defined
echo json_encode($enum); // {"label": "someValue", "value: "someValue" }

枚举定义非常简单(值和标签方法是可选的)

/**
 * @method static self post()
 * @method static self about()
 * @method static self contact()
 */
class PostType extends BaseEnum
{
    protected static function values(): array
    {
        return [
            'post' => 0,
            'about' => 1,
            'contact' => 2
        ];
    }

    protected static function labels(): array
    {
        return [
            'post' => 'Regular posts',
            'about' => 'The about page',
            'contact' => 'The contact page'
        ];
    }
}

另一种方法是使用神奇的__set方法并将枚举设为私有。

e.g.

class Human{
    private $gender;

    public function __set($key, $value){
        if($key == 'day' && !in_array($value, array('Man', 'Woman')){
            new Exception('Wrong value for '.__CLASS__.'->'.$key);
        }
        else{
            $this->$key = $value;
        }
        ...
    }
}

每当类本身之外的代码试图设置类属性时，就会调用这个神奇的方法。 这是从PHP5 - 8工作。

这可能很简单

enum DaysOfWeek {
    Sunday,
    Monday,
    // ...
}

在未来。

枚举类型