(PHP 5 >= 5.1.0, PHP 7, PHP 8)
ArrayObject::exchangeArray — Exchange the array for another one
Exchange the current array with another array or object.
inputThe new array or object to exchange with the current array.
Returns the old array.
Example #1 ArrayObject::exchangeArray() example
<?php
// Array of available fruits
$fruits = array("lemons" => 1, "oranges" => 4, "bananas" => 5, "apples" => 10);
// Array of locations in Europe
$locations = array('Amsterdam', 'Paris', 'London');
$fruitsArrayObject = new ArrayObject($fruits);
// Now exchange fruits for locations
$old = $fruitsArrayObject->exchangeArray($locations);
print_r($old);
print_r($fruitsArrayObject);
?>
以上例程会输出：
Array
(
[lemons] => 1
[oranges] => 4
[bananas] => 5
[apples] => 10
)
ArrayObject Object
(
[0] => Amsterdam
[1] => Paris
[2] => London
)
Looks like PHP8 brings undocumented change to this method signature. Example:
<?php
interface intA {
public function exchangeArray($param);
}
class classB extends ArrayObject implements intA {}
?>
PHP 7.4.13: no errors
PHP 8.0.0: Fatal error: Declaration of ArrayObject::exchangeArray(object|array $array) must be compatible with intA::exchangeArray($param)
It's worth notting that ArrayObject::exchangeArray() doesn't call ArrayObject::offsetSet() internally for each offset/property of the array/object provided in argument.
It's also worth noting the let's say "unexpected" behavior of get/set:
<?php
class MyArrayObject extends ArrayObject
{
public function offsetSet($name, $value)
{
parent::offsetSet($name . '_control', $value);
parent::offsetSet($name, $value);
}
}
$test = new MyArrayObject();
$test->setFlags(\ArrayObject::ARRAY_AS_PROPS);
$test['my_value_1'] = 1;
$test['my_value_1'] = $test['my_value_1'] + 1;
$test['my_value_1'] += 1;
$test['my_value_1'] ++;
++ $test['my_value_1'];
$test->my_value_2 = 1;
$test->my_value_2 = $test->my_value_2 + 1;
$test->my_value_2 += 1;
$test->my_value_2 ++;
++ $test->my_value_2;
print_r($test);
// Prints out:
MyArrayObject Object
(
[storage:ArrayObject:private] => Array
(
[my_value_1_control] => 3
[my_value_1] => 5
[my_value_2_control] => 2
[my_value_2] => 5
)
)
?>
It seems that input array is always passed by reference.
For example if you have an existing array
$array with some values
then you have an arrayobject $o
and then you do this:
$o->exchangeArray($array);
$o->offsetSet('somekey', 'some value');
Now if you check your $array array, it will have
a key 'somekey' with value of 'some value'
I totally did not expect that, I am sure it was a mistake to pass array by reference by default.