ecmall中static变量的使用-model模型代码设计

function &m($model_name, $params = array(), $is_new = false)

{

    static $models = array();

    $model_hash = md5($model_name . var_export($params, true));

    if ($is_new || !isset($models[$model_hash]))

    {

        $model_file = ROOT_PATH . '/includes/models/' . $model_name . '.model.php';

        if (!is_file($model_file))

        {

            /* 不存在该文件，则无法获取模型 */

            return false;

        }

        include_once($model_file);

        $model_name = ucfirst($model_name) . 'Model';

        if ($is_new)

        {

            return new $model_name($params, db());

        }

        $models[$model_hash] = new $model_name($params, db());

    }

    print_r($models[$model_hash]);

    return $models[$model_hash];

}



/**

 * 获取一个业务模型

 *

 * @param string $model_name

 * @param array $params

 * @param bool $is_new

 * @return object

 */

function &bm($model_name, $params = array(), $is_new = false)

{

    static $models = array();

    $model_hash = md5($model_name . var_export($params, true));

    if ($is_new || !isset($models[$model_hash]))

    {

        $model_file = ROOT_PATH . '/includes/models/' . $model_name . '.model.php';

        if (!is_file($model_file))

        {

            /* 不存在该文件，则无法获取模型 */

            return false;

        }

        include_once($model_file);

        $model_name = ucfirst($model_name) . 'BModel';

        if ($is_new)

        {

            return new $model_name($params, db());

        }

        $models[$model_hash] = new $model_name($params, db());

    }



    return $models[$model_hash];

}

使用static变量，当程序退出这段代码的时候，$model并不消失。这样减少了对象建时内存的消耗，有点类似单例模式。

比如这一段代码：

class Model

{

	function  __construct()

	{

		echo 'construct'.'<br>';

	}

}



function &m($model_name, $params = array(), $is_new = false)

{

    static $models = array();

    $model_hash = md5($model_name . var_export($params, true));

    if ($is_new || !isset($models[$model_hash]))

    {

        $model_name = ucfirst($model_name) . 'Model';

        if ($is_new)

        {

            return new Model();

        }

        $models[$model_hash] =  new Model();

    }

    return $models[$model_hash];

}



$s = m('db', array('name'));

$s1 = m('db', array('name'));

 只执行了一次新建过程。