This article mainly introduces the introduction to the 6 predefined interfaces in PHP. This article explains Traversable, Iterator, IteratorAggregate, and ArrayAccess , Serializable, Closure, friends in need can refer to it
PHP predefined 6 interfaces are introduced as follows:
1.Traversable traversal interface
Haha! In fact, it is not an interface that can be used in PHP. Only internal classes can be used. One of its uses is to detect whether a class can be traversed.
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| 1 2 3 4 5 6 7 8 9 10 11 12 13 | Iterator extends Traversable { //Return the element pointed to by the current index cursor abstract public mixed current(void) //Returns the key name of the element pointed to by the current index cursor abstract public scalar key(void) //Move the current index cursor to point to the next element abstract public void next(void) //Reset the index cursor to point to the first element abstract public void rewind(void) //Determine whether the current index cursor points to an element, often used when calling rewind() or next() abstract public boolean valid(void) } |
The above allows a class to implement a basic iteration function. You can see the calling sequence of iteration as follows:
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class myIterator implements Iterator { private $position = 0 ; private $array = array( "firstelement" , "secondelement" , "lastelement" , ); public function __construct () { $this -> position = 0 ; } function rewind () { var_dump ( __METHOD__ ); $this -> position = 0 ; } function current () { var_dump ( __METHOD__ ); return $this -> array [ $this -> position ]; } function key () { var_dump ( __METHOD__ ); return $this -> position ; } function next () { var_dump ( __METHOD__ ); $this -> position ; } function valid () { var_dump ( __METHOD__ ); return isset( $this -> array [ $this -> position ]); } } $it = new myIterator ; foreach( $it as $key => $value ) { var_dump ( $key , $value ); echo "n" ; } |
| 1 2 3 4 5 | IteratorAggregate extends Traversable { //Get external iterator abstract public Traversable getIterator ( void ) } |
getIterator is an instance of a class of Iterator or Traversable interface. Obtain the external iterator as follows to implement iterative access.
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class myData implements IteratorAggregate { public $property1 = "Public property one" ; public $property2 = "Public property two" ; public $property3 = "Public property three" ; public function __construct () { $this -> property4 = "last property" ; } public function getIterator () { return new ArrayIterator ( $this ); } } $obj = new myData ; foreach( $obj as $key => $value ) { var_dump ( $key , $value ); echo "n" ; } |
| 1 2 3 4 5 6 7 | ArrayAccess { /* Method */ abstract public boolean offsetExists (mixed $offset) //Check whether the offset position exists abstract public mixed offsetGet ( mixed $offset ) //Get the value of an offset position abstract public void offsetSet ( mixed $offset , mixed $value ) //Set the value of an offset position abstract public void offsetUnset (mixed $offset) //Reset the value of an offset position } |
The object can be accessed like an array as follows:
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class obj implements arrayaccess { private $container = array(); public function __construct () { $this -> container = array( "one" => 1 , "two" => 2 , "three" => 3 , ); } public function offsetSet ( $offset , $value ) { if ( is_null ( $offset )) { $this -> container [] = $value ; } else { $this -> container [ $offset ] = $value ; } } public function offsetExists ( $offset ) { return isset( $this -> container [ $offset ]); } public function offsetUnset ( $offset ) { unset( $this -> container [ $offset ]); } public function offsetGet ( $offset ) { return isset( $this -> container [ $offset ]) ? $this -> container [ $offset ] : null ; } } $obj = new obj ; var_dump (isset( $obj [ "two" ])); var_dump ( $obj [ "two" ]); unset( $obj [ "two" ]); var_dump (isset( $obj [ "two" ])); $obj [ "two" ] = "A value" ; var_dump ( $obj [ "two" ]); $obj [] = 'Append 1' ; $obj [] = 'Append 2' ; $obj [] = 'Append 3' ; print_r ( $obj ); |
| 1 2 3 4 5 6 | Serializable { /* Method */ abstract public string serialize (void) //String representation of the object abstract public mixed unserialize ( string $serialized ) // Construct object } |
Classes that implement this interface no longer support __sleep() and __wakeup(). Usage is very simple, as long as the serialize method is called when the object is serialized, and the unserialize method is called when deserializing.
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class obj implements Serializable { private $data ; public function __construct () { $this -> data = "My private data" ; } public function serialize () { return serialize ( $this -> data ); } public function unserialize ( $data ) { $this -> data = unserialize ( $data ); } public function getData () { return $this -> data ; } } $obj = new obj ; $ser = serialize ( $obj ); print_r($ser); $newobj = unserialize ( $ser ); print_r($newobj); |
| 1 2 3 4 5 6 | Closure { /* Method */ __construct (void) //Constructor used to prohibit instantiation public static Closure bind ( Closure $closure , object $newthis [, mixed $newscope = 'static' ] ) //Copy a closure and bind the specified $this object and class scope. public Closure bindTo ( object $newthis [, mixed $newscope = 'static' ] ) //Copy the current closure object and bind the specified $this object and class scope. } |
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | class A { private static $sfoo = 1 ; private $ifoo = 2 ; } $cl1 = static function() { return A :: $sfoo ; }; $cl2 = function() { return $this -> ifoo ; }; $bcl1 = Closure :: bind ( $cl1 , null , 'A' ); $bcl2 = Closure :: bind ( $cl2 , new A (), 'A' ); echo $bcl1 (), "n" ; echo $bcl2 (), "n" ; |
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