PHP polymorphic code instance, php polymorphic Instance _php tutorial

PHP polymorphic code instance, PHP polymorphic instance

Polymorphic definition: Only one interface or base class is concerned, not the specific class of an object. (same type, different result)

Here are two examples:

First, we find that the base class defines the standard, and the subclass implements the self-rule. This is a requirement for polymorphism. At the same time, this is a satisfying rewrite; in fact, it is different from the different classes, not strictly satisfies an interface, or the base class programming. Because you call not Stu->showgrade () but their own methods;

Class stu{public  function Showgrade () {    echo "base class";    }} Class Xiaomin extends stu{public  function Showgrade () {    echo ' is son show ';    }} Class Xiaoli extends stu{public  function Showgrade () {    echo ' is son show ';    }} function doit ($obj) {  if (Get_class ($obj)! = "Stu") {    $obj->showgrade ()  }} Doit (new Xiaoli ());d Oit (New Xiaomin ());

The second example: the Dovoice parameter specifies that $obj is a animal, and consciousness is to accept the implementation class object with the interface. The upward transformation. This conforms to the same type, with different results, which is polymorphic;

In fact, in Java it would be animal a = new dog (); Because PHP is a type language. There is no object transformation mechanism.

Interface animal{public  function voice (); Class Cat implements animal{public  function voice () {    echo] miao~~~
";  }} Class Dog implements animal{public  function voice () {    echo ' Wang ~ ~ ~
";  }} function Dovoice (animal $obj) {  $obj->voice ();} Dovoice (New Dog ());d Ovoice (New Cat ());

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