ArrayObject::exchangeArray()

(PHP 5 >= 5.1.0, PHP 7)

Exchange the array for another one

说明

publicArrayObject::exchangeArray(mixed $input): array

Exchange the current array with another array or object.

参数

$input

The new array or object to exchange with the current array.

返回值

Returns the old array.

范例

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
)

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.

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
    )
)
?>