Data::Grove(3)        User Contributed Perl Documentation       Data::Grove(3)

       Data::Grove -- support for deeply nested structures

        use Data::Grove;

        $object = MyPackage->new;

        package MyPackage;
        @ISA = qw{Data::Grove};

       "Data::Grove" provides support for deeply nested tree or graph struc-
       tures.  "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::Par-
       ent" 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

       "Data::Grove" objects do not contain parent references, Perl garbage
       collection will delete them when no longer referenced and sub-struc-
       tures 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

       new( PROPERTIES )
           Return a new object blessed into the SubClass, with the given prop-
           erties.  PROPERTIES may either be a list of key/value pairs, a sin-
           gle 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 under-
           neath still refer to the original objects.

       Ken MacLeod,


perl v5.8.6                       2003-10-21                    Data::Grove(3)