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This article focuses on "introduction of several predefined interfaces in PHP". Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn "introduction to several predefined interfaces in PHP".

Six predefined APIs for PHP are described as follows:

1.Traversable traversal interface

He he! 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.

If ($class instanceof Traversable) {/ / foreach}

2.Iterator iterator interface

Interface Summary:

Iterator extends Traversable {/ / return the element abstract public mixed current (void) pointed to by the current index cursor / / return 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 the first element abstract public void rewind (void) / / determine whether the current index cursor points to an element Abstract public boolean valid (void)} is often used when calling rewind () or next ()

The above allows a class to implement a basic iteration function. You can see the call sequence of the iteration as follows:

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";}

3.IteratorAggregate aggregate iterator interface

Interface Summary:

IteratorAggregate extends Traversable {/ / get external iterator abstract public Traversable getIterator (void)}

GetIterator is an instance of a class with an Iterator or Traversable interface. Get the external iterator for iterative access as follows.

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";}

4.ArrayAccess array access interface

Interface Summary:

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}

You can access objects as follows:

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)

5.Serializable Serialization Interface

Interface Summary:

The string of Serializable {/ * method * / abstract public string serialize (void) / / object represents abstract public mixed unserialize (string $serialized) / / Construction object}

Classes that implement this interface no longer support _ _ sleep () and _ _ wakeup (). It is easy to use, as long as the serialize method is called when the object is serialized, and the unserialize method is called when deserialized.

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 = newobj; $ser = serialize ($obj); print_r ($ser); $newobj = unserialize ($ser); print_r ($newobj)

6.Closure

Interface Summary:

The Closure {/ * method * / _ construct (void) / / forbids the instantiated constructor public static Closure bind (Closure $closure, object $newthis [, mixed $newscope = 'static']) / / copies a closure that binds the specified $this object and class scope. Public Closure bindTo (object $newthis [, mixed $newscope = 'static']) / / copies the current closure object, binding the specified $this object and class scope. } 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" At this point, I believe you have a deeper understanding of "several predefined interfaces in PHP". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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