Data::Grove::Parent - provide parent properties to Data::Grove objects
use Data::Grove::Parent; $root = $object->root; $rootpath = $object->rootpath; $tied = $object->add_magic([ $parent ]); $node = Data::Grove::Parent->new($hash [, $parent]); $node_list = Data::Grove::ParentList->new($array [, $parent]);
Data::Grove::Parent is an extension to Data::Grove that adds `
Parent' and `
Raw' properties to Data::Grove objects and methods for returning the root node of a grove, a list of nodes between and including the root node and the current node, and a method that creates parented nodes.
Data::Grove::Parent works by creating a Perl ``tied'' object that contains a parent reference (`
Parent') and a reference to the original Data::Grove object (`
Raw'). Tying-magic is used so that every time you reference the Data::Grove::Parent object it actually references the underlying raw object.
When you retrieve a list or a property of the Raw object, Data::Grove::Parent automatically adds magic to the returned list or node. This means you only call `add_magic()' once to create the first Data::Grove::Parent object and then use the grove objects like you normally would.
The most obvious use of this is so you don't have to call a `
delete' method when you want to release a grove or part of a grove; since Data::Grove and Data::Grove::Parent objects have no cyclic references, Perl can garbage collect them normally.
A secondary use is to allow you to reuse grove or property set fragments in multiple trees. WARNING: Data::Grove currently does not protect you from creating your own cyclic references! This could lead to infinite loops if you don't take care to avoid them.
root()' returns the root node if `
$object' is a `
Data::Grove::Parent' object. `
rootpath()' returns an array of all the nodes between and including the root node and `
- $tied = $object->add_magic([ $parent ])
add_magic()' returns a
Data::Grove::Parentobject with `
$object' as it's `
Raw' object. If `
$parent' is given, that becomes the tied object's parent object.
Ken MacLeod, email@example.com