PHP ArrayObject inner workings
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26-04-2021 - |
質問
Where can I find the ArrayObject's complete source code (in PHP)?
What I dont understand is why you can use the "arrow" when add an element to your ArrayObject, for example:
$a = new ArrayObject();
$a['arr'] = 'array data';
$a->prop = 'prop data'; //here it is
You can see $a->prop = 'prop data';
is used.
Is there any magic method or what was used, and how PHP knows for example that $a['prop']
and $a->prop
means the same ? (in this context)
解決
Yes, it is magic and it can be accomplished directly in PHP. Take look at Overloading http://www.php.net/manual/en/language.oop5.overloading.php
You can use __get()
and __set
in a class to do this. To make objects behave like arrays, you have to implement http://www.php.net/manual/en/class.arrayaccess.php
This is my example code:
<?php
class MyArrayObject implements Iterator, ArrayAccess, Countable
{
/** Location for overloaded data. */
private $_data = array();
public function __set($name, $value)
{
$this->_data[$name] = $value;
}
public function __get($name)
{
if (array_key_exists($name, $this->_data)) {
return $this->_data[$name];
}
$trace = debug_backtrace();
trigger_error(
'Undefined property via __get(): ' . $name .
' in ' . $trace[0]['file'] .
' on line ' . $trace[0]['line'],
E_USER_NOTICE);
return null;
}
/** As of PHP 5.1.0 */
public function __isset($name)
{
return isset($this->_data[$name]);
}
/** As of PHP 5.1.0 */
public function __unset($name)
{
unset($this->_data[$name]);
}
public function offsetSet($offset, $value) {
if (is_null($offset)) {
$this->_data[] = $value;
} else {
$this->_data[$offset] = $value;
}
}
public function offsetExists($offset) {
return isset($this->_data[$offset]);
}
public function offsetUnset($offset) {
unset($this->_data[$offset]);
}
public function offsetGet($offset) {
return isset($this->_data[$offset]) ? $this->_data[$offset] : null;
}
public function count(){
return count($this->_data);
}
public function current(){
return current($this->_data);
}
public function next(){
return next($this->_data);
}
public function key(){
return key($this->_data);
}
public function valid(){
return key($this->_data) !== null;
}
public function rewind(){
reset($this->_data);
}
}
Instead of current($a)
, next($a)
use $a->current()
, $a->next()