NAME¶
Data::Grove -- support for deeply nested structures
SYNOPSIS¶
use Data::Grove;
$object = MyPackage->new;
package MyPackage;
@ISA = qw{Data::Grove};
DESCRIPTION¶
"Data::Grove" provides support for deeply nested tree or graph
structures. "Data::Grove" is intended primarily for Perl module
authors writing modules with many types or classes of objects that need to be
manipulated and extended in a consistent and flexible way.
"Data::Grove" is best used by creating a core set of ``data'' classes
and then incrementally adding functionality to the core data classes by using
``extension'' modules. One reason for this design is so that the data classes
can be swapped out and the extension modules can work with new data sources.
For example, these other data sources could be disk-based, network-based or
built on top of a relational database.
Two extension modules that come with "Data::Grove" are
"Data::Grove::Parent" and "Data::Grove::Visitor".
"Data::Grove::Parent" adds a `"Parent"' property to grove
objects and implements a `"root"' method to grove objects to return
the root node of the tree from anywhere in the tree and a
`"rootpath"' method to return a list of nodes between the root node
and ``this'' node. "Data::Grove::Visitor" adds callback methods
`"accept"' and `"accept_name"' that call your handler or
receiver module back by object type name or the object's name.
"Data::Grove" objects do not contain parent references, Perl garbage
collection will delete them when no longer referenced and sub-structures can
be shared among several structures. "Data::Grove::Parent" is used to
create temporary objects with parent pointers.
Properties of data classes are accessed directly using Perl's hash functions
(i.e. `"$object->{Property}"'). Extension modules may also define
properties that they support or use, for example Data::Grove::Parent adds
`"Parent"' and `"Raw"' properties and Visitor depends on
`"Name"' and `"Content"' properties.
See the module "XML::Grove" for an example implementation of
"Data::Grove".
METHODS¶
- new( PROPERTIES )
- Return a new object blessed into the SubClass, with the given properties.
PROPERTIES may either be a list of key/value pairs, a single hash
containing key/value pairs, or an existing "Data::Grove" object.
If an existing "Data::Grove" is passed to `"new()"', a
shallow copy of that object will be returned. A shallow copy means that
you are returned a new object, but all of the objects underneath still
refer to the original objects.
AUTHOR¶
Ken MacLeod, ken@bitsko.slc.ut.us
SEE ALSO¶
perl(1)