类默认公共变量可以从 php 中的数组动态定义吗?
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13-12-2019 - |
题
我有一个事件类,用于将数据插入/更新到我的数据库中。有没有一种方法可以从 db_fields 数组创建公共变量,这样我就不必复制数据?
这是我目前有效的结构......
class event{
protected static $table_name='tName';
protected static $db_fields = array('field1','field2','field3','field4','field5');
public $field1;
public $field2;
public $field3;
public $field4;
public $field5;
}
我想要有这样的东西..
class event{
protected static $table_name='tName';
protected static $db_fields = array('field1','field2','field3','field4','field5');
function __construct() {
create_public_vars_here($db_fields);
}
}
谢谢!
解决方案
您可以尝试以下操作:
class event{
protected static $table_name='tName';
protected static $db_fields = array('field1','field2','field3','field4','field5');
function __construct() {
foreach (self::$db_fields as $var) {
$this->$var = $whateverDefaultValue;
}
// After the foreach loop, you'll have a bunch of properties of this object with the variable names being the string values of the $db_fiels.
// For example, you'll have $field1, $field2, etc and they will be loaded with the value $whateverDefaultValue (probably want to set it to null).
}
}
. 其他提示
您可以使用魔术设置器/获取器:
class event{
protected static $table_name='tName';
protected static $db_fields = array('field1','field2','field3','field4','field5');
public function __get($key)
{
if(!in_array($key, static::$db_fields))
throw new Exception( $key . " doesn't exist.");
return $this -> $key;
}
public function __set($key, $value)
{
if(!in_array($key, static::$db_fields))
throw new Exception( $key . " doesn't exist.");
$this -> $key = $value;
}
}
这样你就可以确保不会达到列表之外的值:
$event -> field1 = 'hello'; // --> OK
$event -> field17 = 'hello'; // --> Exception: field17 doesn't exist
echo $event -> field1; // --> OK
echo $event -> field17; // --> Exception: field17 doesn't exist
至于在代码中明确的公共变量声明,只要您不必迭代对象,就不需要 - 但在这种情况下,您将实现 Iterator
基于您的静态字段的界面。
使用突变分子:
class event{
protected static $table_name='tName';
protected static $db_fields = array('field1','field2','field3','field4','field5');
function getVars($var) {
if(!in_arrary($this->db_fields[$var])) {
return false;
} else {
return $this->db_fields[$var];
}
}
}
.
然后您可以如下访问它:
$eventObject->getVars('field3');
.
或者,如果您没有从类中创建对象:
event::getVars('field3');
.
编辑:从复杂的东西的精神使您没有违规,代码添加了。
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