通常当我想创建一个接受不同类型参数的类构造函数时,我将使用krodgy重载原则,在构造函数定义中不定义任何args: 例如对于ECEF坐标类构造函数,我希望它接受$ x,$ y和$ z参数,或者接受包含x,y和z值的单个数组参数,或者接受我创建的单个LatLong对象构造函数看起来像:
function __construct()
{
// Identify if any arguments have been passed to the constructor
if (func_num_args() > 0) {
$args = func_get_args();
// Identify the overload constructor required, based on the datatype of the first argument
$argType = gettype($args[0]);
switch($argType) {
case 'array' :
// Array of Cartesian co-ordinate values
$overloadConstructor = 'setCoordinatesFromArray';
break;
case 'object' :
// A LatLong object that needs converting to Cartesian co-ordinate values
$overloadConstructor = 'setCoordinatesFromLatLong';
break;
default :
// Individual Cartesian co-ordinate values
$overloadConstructor = 'setCoordinatesFromXYZ';
break;
}
// Call the appropriate overload constructor
call_user_func_array(array($this,$overloadConstructor),$args);
}
} // function __construct()
我正在寻找另一种选择:提供一个带有$ x,$ y和$ z作为定义参数的直接构造函数,并提供createECEFfromArray()和createECEFfromLatLong()的静态方法,用于处理x的所有必要提取,y和z;然后使用标准构造函数创建一个新的ECEF对象,并返回
从OO纯粹主义者的角度来看哪个选项更清晰?
答案 0 :(得分:0)
我一直在考虑这里提供的建议以及其他人清理对象构造函数的重载。我认为,我所决定的方法是优雅,易于实现且使用直观。
作为解决方案,我决定为构造函数参数实现一个通用接口: 我开始创建一个界面。
interface Geodetic_XyzFormat
{
public function getX();
public function getY();
public function getZ();
}
我添加了一个抽象来实现接口中定义的getter,以及setter和一些在几个子类中通用的其他方法。
abstract class Geodetic_ECEF_Coordinates implements Geodetic_XyzFormat
{
protected $_xCoordinate;
protected $_yCoordinate;
protected $_zCoordinate;
protected function setX($xCoordinate)
{
$this->_xCoordinate = $xCoordinate;
}
public function getX()
{
return $this->_xCoordinate;
}
protected function setY($yCoordinate)
{
$this->_yCoordinate = $yCoordinate;
}
public function getY()
{
return $this->_yCoordinate;
}
protected function setZ($zCoordinate)
{
$this->_zCoordinate = $zCoordinate;
}
public function getZ()
{
return $this->_zCoordinate;
}
protected function setCoordinates($xDistance,
$yDistance,
$zDistance,
$uom)
{
$this->setX(
($xDistance instanceof Geodetic_Distance) ? $xDistance : new Geodetic_Distance($xDistance, $uom)
);
$this->setY(
($yDistance instanceof Geodetic_Distance) ? $yDistance : new Geodetic_Distance($yDistance, $uom)
);
$this->setZ(
($zDistance instanceof Geodetic_Distance) ? $zDistance : new Geodetic_Distance($zDistance, $uom)
);
}
}
对于我的主类构造函数,我输入提示它接受扩展接口定义的类:
class Geodetic_ECEF_TestClass
{
protected $_xCoordinate;
protected $_yCoordinate;
protected $_zCoordinate;
public function __construct(Geodetic_XyzFormat $xyzCoordinates = NULL)
{
if (!is_null($xyzCoordinates)) {
$this->_xCoordinate = $xyzCoordinates->getX();
$this->_yCoordinate = $xyzCoordinates->getY();
$this->_zCoordinate = $xyzCoordinates->getZ();
return;
}
// Defaults
$this->_xCoordinate = new Geodetic_Distance();
$this->_yCoordinate = new Geodetic_Distance();
$this->_zCoordinate = new Geodetic_Distance();
}
}
最后,我创建了几个扩展我的抽象的类,每个类都处理构造函数参数的不同选项;在这种情况下,一个值数组和各个值......稍后我将编写LatLong变量,但它将使用相同的基本原理并以相同的方式扩展Geodetic_ECEF_Coordinates。
class Geodetic_ECEF_CoordinateArray extends Geodetic_ECEF_Coordinates
{
public function __construct(array $coordinates = NULL, $uom = Geodetic_Distance::METRES)
{
if (is_null($coordinates))
throw new Geodetic_Exception('An array of vector coordinates must be passed');
if (count($coordinates) == 3) {
list ($xDistance, $yDistance, $zDistance) = array_values($coordinates);
} else {
throw new Geodetic_Exception('Invalid number of vectors in array');
}
$this->setCoordinates($xDistance, $yDistance, $zDistance, $uom);
}
}
class Geodetic_ECEF_CoordinateValues extends Geodetic_ECEF_Coordinates
{
public function __construct($xDistance = NULL,
$yDistance = NULL,
$zDistance = NULL,
$uom = Geodetic_Distance::METRES)
{
$this->setCoordinates($xDistance, $yDistance, $zDistance, $uom);
}
}
现在,当我实例化一个ECEF对象时,我将它传递给相应的Geodetic_XyzFormat对象:
// Nothing passed to constructor
$dummyECEF1 = new Geodetic_ECEF_TestClass();
var_dump($dummyECEF1);
// Array of values passed to constructor
$dummyECEF2 = new Geodetic_ECEF_TestClass(
new Geodetic_ECEF_CoordinateArray(
array(1.2, 3.4, 5.6)
)
);
var_dump($dummyECEF2);
// Individual values passed to constructor
$dummyECEF3 = new Geodetic_ECEF_TestClass(
new Geodetic_ECEF_CoordinateValues(7.8, 9.1, 2.3)
);
var_dump($dummyECEF3);
// Individual values passed to constructor (including a NULL, which should be treated as a 0)
$dummyECEF4 = new Geodetic_ECEF_TestClass(
new Geodetic_ECEF_CoordinateValues(4.5, NULL, 6.7)
);
var_dump($dummyECEF4);
$xDistance = new Geodetic_Distance(11.11, Geodetic_Distance::MILES);
$yDistance = new Geodetic_Distance(22.22, Geodetic_Distance::MILES);
$zDistance = new Geodetic_Distance(33.33, Geodetic_Distance::MILES);
// Array of distances passed to constructor
$dummyECEF5 = new Geodetic_ECEF_TestClass(
new Geodetic_ECEF_CoordinateArray(
array($xDistance, $yDistance, $zDistance)
)
);
var_dump($dummyECEF5);
$xDistance = new Geodetic_Distance(44.44, Geodetic_Distance::MILES);
$yDistance = new Geodetic_Distance(55.55, Geodetic_Distance::MILES);
$zDistance = new Geodetic_Distance(66.66, Geodetic_Distance::MILES);
// Individual distances passed to constructor
$dummyECEF6 = new Geodetic_ECEF_TestClass(
new Geodetic_ECEF_CoordinateValues($xDistance, $yDistance, $zDistance)
);
var_dump($dummyECEF6);
$xDistance = new Geodetic_Distance(11.11, Geodetic_Distance::MILES);
$yDistance = new Geodetic_Distance(22.22, Geodetic_Distance::KILOMETRES);
$zDistance = new Geodetic_Distance(33.33, Geodetic_Distance::MILES);
// Array of mixed values and distances passed to constructor
$dummyECEF7 = new Geodetic_ECEF_TestClass(
new Geodetic_ECEF_CoordinateArray(
array(11, $yDistance, 33),
Geodetic_Distance::MILES
)
);
var_dump($dummyECEF7);
$xDistance = new Geodetic_Distance(44.44, Geodetic_Distance::MILES);
$yDistance = new Geodetic_Distance(55.55, Geodetic_Distance::KILOMETRES);
$zDistance = new Geodetic_Distance(66.66, Geodetic_Distance::INCHES);
// Individual mixture of distances and values passed to constructor
$dummyECEF8 = new Geodetic_ECEF_TestClass(
new Geodetic_ECEF_CoordinateValues($xDistance, 55, $zDistance, Geodetic_Distance::NAUTICAL_MILES)
);
var_dump($dummyECEF8);
它不需要针对不同参数类型的所有kludgy测试(无论是在工厂中,还是在我的主类中),也不需要使用静态(因此编写单元测试应该非常简单)
感谢所有提出建议并给我思考的人