[Document] clone usage in PHP

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Clone usage in PHP

Official documents: http://cn2.php.net/__clone

In most cases, we do not need to completely copy an object to obtain its attributes. However, you need to: If you have a GTK window object, the object holds window-related resources. You may want to copy a new window to keep all attributes the same as the original window, but it must be a new object (because if it is not a new object, changes in one window will affect the other window ). Another case is: If object A contains the reference of object B, when you copy object A, you want to use the object instead of object B but a copy of object B, then you must get a copy of object.

Object replication can be completed by using the clone keyword (if possible, the _ clone () method of the object will be called ). The _ clone () method in the object cannot be called directly.

 

Demo 1

<? PHP  Class  Person {  Private   $ Name  ; Private   $ Age  ;  Private   $ ID  ;  Function _ Construct ( $ Name , $ Age  ){  $ This -> Name = $ Name  ;  $ This -> Age = $ Age ;}  Function Setid ( $ ID  ){  $ This -> Id = $ ID  ;}  Function  _ Clone (){  $ This -> Id = 0 ;}}  Print "<PRE>" ;  $ Person = New Person ("Bob", 44 );  $ Person -& Gt; setid (343 );  $ Person2 = Clone   $ Person  ;  Print_r ( $ Person  );  Print_r ( $ Person2  );  Print "</PRE>" ; ?>

DEMO 2

<? PHP  Class  Account {  Public   $ Balance  ;  Function _ Construct ( $ Balance  ){  $ This -> Balance = $ Balance  ;}}  Class  Person {  Private  $ Name  ;  Private   $ Age  ;  Private   $ ID  ;  Public   $ Account  ;  Function _ Construct ( $ Name , $ Age , Account $ Account  ){ $ This -> Name = $ Name  ;  $ This -> Age = $ Age  ;  $ This -> Account = $ Account  ;}  Function Setid ( $ ID  ){  $ This -> Id = $ ID  ;} Function  _ Clone (){  $ This -> Id = 0 ;}}  $ Person = New Person ("Bob", 44, New Account (200 ));  $ Person -& Gt; setid (343 );  $ Person2 = Clone   $ Person  ; //  Give $ person some money  $ Person -> Account-> balance + = 10 ;  //  $ Person2 sees the credit too  Print   $ Person2 -> Account-> Balance;  //  Output: // 210 ?>