readme.md

Predefined Interfaces and Classes

http://php.net/manual/en/reserved.interfaces.php

---

Traversable interface

http://php.net/manual/en/class.traversable.php

Interface to detect if a class is traversable using foreach.

Abstract base interface that cannot be implemented alone. Instead it must be implemented by either IteratorAggregate or Iterator.

<?php
/**
 * Interface to detect if a class is traversable using &foreach;.
 * @link http://php.net/manual/en/class.traversable.php
 */
interface Traversable extends iterable {
}

---

Iterator

http://php.net/manual/en/class.iterator.php

example

Interface for external iterators or objects that can be iterated themselves internally.

P/s: Used in foreach

<?php
/**
 * Interface for external iterators or objects that can be iterated
 * themselves internally.
 * @link http://php.net/manual/en/class.iterator.php
 */
interface Iterator extends Traversable {

    /**
     * Return the current element
     * @link http://php.net/manual/en/iterator.current.php
     * @return mixed Can return any type.
     * @since 5.0.0
     */
    public function current();

    /**
     * Move forward to next element
     * @link http://php.net/manual/en/iterator.next.php
     * @return void Any returned value is ignored.
     * @since 5.0.0
     */
    public function next();

    /**
     * Return the key of the current element
     * @link http://php.net/manual/en/iterator.key.php
     * @return mixed scalar on success, or null on failure.
     * @since 5.0.0
     */
    public function key();

    /**
     * Checks if current position is valid
     * @link http://php.net/manual/en/iterator.valid.php
     * @return boolean The return value will be casted to boolean and then evaluated.
     * Returns true on success or false on failure.
     * @since 5.0.0
     */
    public function valid();

    /**
     * Rewind the Iterator to the first element
     * @link http://php.net/manual/en/iterator.rewind.php
     * @return void Any returned value is ignored.
     * @since 5.0.0
     */
    public function rewind();
}

<?php
/**
 * Interface to detect if a class is traversable using &foreach;.
 * @link http://php.net/manual/en/class.traversable.php
 */
interface Traversable extends iterable {
}

<?php

/**
 * @link https://wiki.php.net/rfc/iterable
 */
interface iterable {}

---

IteratorAggregate interface

Example

Interface to create an external Iterato

<?php
/**
 * Interface to create an external Iterator.
 * @link http://php.net/manual/en/class.iteratoraggregate.php
 */
interface IteratorAggregate extends Traversable {

    /**
     * Retrieve an external iterator
     * @link http://php.net/manual/en/iteratoraggregate.getiterator.php
     * @return Traversable An instance of an object implementing <b>Iterator</b> or
     * <b>Traversable</b>
     * @since 5.0.0
     */
    public function getIterator();
}

---

ArrayAccess interface

http://php.net/manual/en/class.arrayaccess.php

Example

Interface to provide accessing objects as arrays.

<?php
/**
 * Interface to provide accessing objects as arrays.
 * @link http://php.net/manual/en/class.arrayaccess.php
 */
interface ArrayAccess {

    /**
     * Whether a offset exists
     * @link http://php.net/manual/en/arrayaccess.offsetexists.php
     * @param mixed $offset <p>
     * An offset to check for.
     * </p>
     * @return boolean true on success or false on failure.
     * </p>
     * <p>
     * The return value will be casted to boolean if non-boolean was returned.
     * @since 5.0.0
     */
    public function offsetExists($offset);

    /**
     * Offset to retrieve
     * @link http://php.net/manual/en/arrayaccess.offsetget.php
     * @param mixed $offset <p>
     * The offset to retrieve.
     * </p>
     * @return mixed Can return all value types.
     * @since 5.0.0
     */
    public function offsetGet($offset);

    /**
     * Offset to set
     * @link http://php.net/manual/en/arrayaccess.offsetset.php
     * @param mixed $offset <p>
     * The offset to assign the value to.
     * </p>
     * @param mixed $value <p>
     * The value to set.
     * </p>
     * @return void
     * @since 5.0.0
     */
    public function offsetSet($offset, $value);

    /**
     * Offset to unset
     * @link http://php.net/manual/en/arrayaccess.offsetunset.php
     * @param mixed $offset <p>
     * The offset to unset.
     * </p>
     * @return void
     * @since 5.0.0
     */
    public function offsetUnset($offset);
}

---

Serializable interface

http://php.net/manual/en/class.serializable.php

Interface for customized serializing.

<?php

/**
 * Interface for customized serializing.
 * @link http://php.net/manual/en/class.serializable.php
 */
interface Serializable {

    /**
     * String representation of object
     * @link http://php.net/manual/en/serializable.serialize.php
     * @return string the string representation of the object or null
     * @since 5.1.0
     */
    public function serialize();

    /**
     * Constructs the object
     * @link http://php.net/manual/en/serializable.unserialize.php
     * @param string $serialized <p>
     * The string representation of the object.
     * </p>
     * @return void
     * @since 5.1.0
     */
    public function unserialize($serialized);
}

---