Saving tree-like structure - perl

Question

I have following tree-like structure where each level is represented by separate class:
Book ------ Page ------ Line
1 n 1 n
Each class has a property that holds all its members (e/g/ Book::pages, as array of blessed refs), some properties specific to the level (e.g. Book::author) as well as some methods to add/remove its members.
Now I want to save/load all the data to/from a single file. It's not going to be a relational DB (most probably YAML will be used), so basically what I need to get at some point is something like:
my $book = {
author => "Fred Flinstone",
name => "My Favorite Stones",
pages => [
{
number => 1,
footer => "Dedicated to Wilma",
lines => [ ],
},
{
number => 2,
lines => [
{ text => "Preface", style => "h1" },
{ text => "This book is about my favorite stones:" },
{ text => "Marble" },
# ...
]
},
# ...
]
};
Should there be one smart pair of methods in Book that knows about all member classes? Or should each class implement part of it so that e.g. Line::save returned something like { text => "Marble" }?
What is the correct way to implement this? I would like solution that is as least as possible bounded to the actual data. What if I decide tomorrow to add Page::bookmarks and want to save Bookmarks as well?
Oh, and I'm using Moose, although that should not make much difference.

Answer 1

If you're using Moose, I would recommend looking at MooseX::Storage to handle this. You would use this module inside your package then add with Storage('format' => 'YAML', 'io' => 'File');.
This quick example may get you started:
package Book;
use Moose;
use MooseX::Storage;
with Storage('format' => 'YAML', 'io' => 'File');
...
1;
my $book = Book->new();
...
# to store object
$book->store('book.yml');
# to get object back
my $book2 = Book->load('book.yml');