[英]PHP use abstract class or interface?
在這段代碼中,最好是使用抽象類代替接口,還是現在好呢? 如果是這樣,為什么?
/** contract for all flyable vehicles **/
interface iFlyable {
public function fly();
}
/* concrete implementations of iFlyable interface */
class JumboJet implements iFlyable {
public function fly() {
return "Flying 747!";
}
}
class FighterJet implements iFlyable {
public function fly() {
return "Flying an F22!";
}
}
class PrivateJet implements iFlyable {
public function fly() {
return "Flying a Lear Jet!";
}
}
/** contract for conrete Factory **/
/**
* "Define an interface for creating an object, but let the classes that implement the interface
* decide which class to instantiate. The Factory method lets a class defer instantiation to
* subclasses."
**/
interface iFlyableFactory {
public static function create( $flyableVehicle );
}
/** concrete factory **/
class JetFactory implements iFlyableFactory {
/* list of available products that this specific factory makes */
private static $products = array( 'JumboJet', 'FighterJet', 'PrivateJet' );
public static function create( $flyableVehicle ) {
if( in_array( $flyableVehicle, JetFactory::$products ) ) {
return new $flyableVehicle;
} else {
throw new Exception( 'Jet not found' );
}
}
}
$militaryJet = JetFactory::create( 'FighterJet' );
$privateJet = JetFactory::create( 'PrivateJet' );
$commercialJet = JetFactory::create( 'JumboJet' );
界面更加靈活。 這樣,並不是所有蒼蠅都被強制從同一個基類繼承(php不支持多重繼承)
所以
class bird extends animal implements flyable
class plane extends machine implements flyable
class cloud implements flyable
有時並不需要靈活性。
抽象類還可以提供函數定義,如果多個飛行類需要相同的fly()方法,則可以減少代碼重復
希望能幫助您了解您的選擇
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