Zend_Memory component operates with the following concepts:
Locked memory object
Movable memory object
The memory manager generates memory objects (locked or movable) by request of user application and returns them wrapped into a memory container object.
The memory container has a virtual or actual value attribute of string type. This attribute contains the data value specified at memory object creation time.
You can operate with this value attribute as an object property:
$memObject = $memoryManager->create($data);
$memObject->value = $newValue;
$memObject->value[$index] = '_';
$memObject->value = substr($memObject->value, $start, $length);
If you are using a PHP version earlier than 5.2, use the getRef() method instead of accessing the value property directly.
Locked memory objects are always stored in memory. Data stored in locked memory are never swapped to the cache backend.
Movable memory objects are transparently swapped and loaded
to/from the cache backend by
Zend_Memory when it's necessary.
The memory manager doesn't swap objects with size less than the specified minimum, due to performance considerations. See this section for more details.