php链式操作的实现

<?PHP

class sql{

    private $sql=array("from"=>"","where"=>"","order"=>"","limit"=>"");

 

    public function from($tableName) {

        $this->sql["from"]="FROM ".$tableName;

        return $this;

    }

 

    public function where($_where='1=1') {

        $this->sql["where"]="WHERE ".$_where;

        return $this;

    }

 

    public function order($_order='id DESC') {

        $this->sql["order"]="ORDER BY ".$_order;

        return $this;

    }

 

    public function limit($_limit='30') {

        $this->sql["limit"]="LIMIT 0,".$_limit;

        return $this;

    }

    public function select($_select='*') {

        return "SELECT ".$_select." ".(implode(" ",$this->sql));

    }

}

 

$sql =new sql();

 

echo $sql->from("testTable")->where("id=1")->order("id DESC")->limit(10)->select();

//输出 SELECT * FROM testTable WHERE id=1 ORDER BY id DESC LIMIT 0,10

?>

<?PHP

class String

{

    public $value;

 

    public function __construct($str=null)

    {

        $this->value = $str;

    }

 

    public function __call($name,$args)

    {

        $this->value = call_user_func($name,$this->value,$args[0]);

        return $this;

    }

 

    public function strlen()

    {

        return strlen($this->value);

    }

}

$str = new String('01389');

echo $str->trim('0')->strlen();

// 输出结果为 4；trim('0')后$str为"1389"

?>