本文实例讲述了php中enum(枚举)用法。分享给大家供大家参考，具体如下：
php其实有enum类库的，需要安装perl扩展，所以不是php的标准扩展，因此代码的实现需要运行的php环境支持。
（1）扩展类库splenum类。该类的摘要如下：
splenum extends spltype {
/* constants */
const null __default = null ;
/* 方法 */
public array getconstlist ([ bool $include_default = false ] )
/* 继承的方法 */
spltype::__construct ([ mixed $initial_value [, bool $strict ]] )
}
使用示例：
<?php
class month extends splenum {
const __default = self::january;
const january = 1;
const february = 2;
const march = 3;
const april = 4;
const may = 5;
const june = 6;
const july = 7;
const august = 8;
const september = 9;
const october = 10;
const november = 11;
const december = 12;
}
echo new month(month::june) . php_eol;
try {
new month(13);
} catch (unexpectedvalueexception $uve) {
echo $uve->getmessage() . php_eol;
}
?>
输出结果：
6 value not a const in enum month
（2）自定义的enum类库
<?php
/**
* abstract class that enables creation of php enums. all you
* have to do is extend this class and define some constants.
* enum is an object with value from on of those constants
* (or from on of superclass if any). there is also
* __default constat that enables you creation of object
* without passing enum value.
*
* @author marijan Šuflaj <msufflaj32@gmail.com>
* @link http://php4every1.com
*/
abstract class enum {
/**
* constant with default value for creating enum object
*/
const __default = null;
private $value;
private $strict;
private static $constants = array();
/**
* returns list of all defined constants in enum class.
* constants value are enum values.
*
* @param bool $includedefault if true, default value is included into return
* @return array array with constant values
*/
public function getconstlist($includedefault = false) {
$class = get_class($this);
if (!array_key_exists($class, self::$constants)) {
self::populateconstants();
}
return $includedefault ? array_merge(self::$constants[__class_], array(
"__default" => self::__default
)) : self::$constants[__class_];
}
/**
* creates new enum object. if child class overrides __construct(),
* it is required to call parent::__construct() in order for this
* class to work as expected.
*
* @param mixed $initialvalue any value that is exists in defined constants
* @param bool $strict if set to true, type and value must be equal
* @throws unexpectedvalueexception if value is not valid enum value
*/
public function __construct($initialvalue = null, $strict = true) {
$class = get_class($this);
if (!array_key_exists($class, self::$constants)) {
self::populateconstants();
}
if ($initialvalue === null) {
$initialvalue = self::$constants[$class]["__default"];
}
$temp = self::$constants[$class];
if (!in_array($initialvalue, $temp, $strict)) {
throw new unexpectedvalueexception("value is not in enum " . $class);
}
$this->value = $initialvalue;
$this->strict = $strict;
}
private function populateconstants() {
$class = get_class($this);
$r = new reflectionclass($class);
$constants = $r->getconstants();
self::$constants = array(
$class => $constants
);
}
/**
* returns string representation of an enum. defaults to
* value casted to string.
*
* @return string string representation of this enum's value
*/
public function __tostring() {
return (string) $this->value;
}
/**
* checks if two enums are equal. only value is checked, not class type also.
* if enum was created with $strict = true, then strict comparison applies
* here also.
*
* @return bool true if enums are equal
*/
public function equals($object) {
if (!($object instanceof enum)) {
return false;
}
return $this->strict ? ($this->value === $object->value)
: ($this->value == $object->value);
}
}
使用示例如下：
class myenum extends enum {
const hi = "hi";
const by = "by";
const number = 1;
const __default = self::by;
}
var_dump(new myenum(myenum::hi));
var_dump(new myenum(myenum::by));
//use __default
var_dump(new myenum());
try {
new myenum("i don't exist");
} catch (unexpectedvalueexception $e) {
var_dump($e->getmessage());
}
输出结果如下：
object(myenum)#1 (2) {
["value":"enum":private]=>
string(2) "hi"
["strict":"enum":private]=>
bool(true)
}
object(myenum)#1 (2) {
["value":"enum":private]=>
string(2) "by"
["strict":"enum":private]=>
bool(true)
}
object(myenum)#1 (2) {
["value":"enum":private]=>
string(2) "by"
["strict":"enum":private]=>
bool(true)
}
string(27) "value is not in enum myenum"
希望本文所述对大家php程序设计有所帮助。
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