SYNOPSIS use Tree::Create::Callback qw(create_tree_using_callback); use Tree::Object::Hash; # for nodes # create a tree of height 4 containing 1 + 2 + 4 + 8 nodes my $tree = create_tree_using_callback( sub { my ($parent, $level, $seniority) = @_; # we should return ($node, $num_children) return (Tree::Object::Hash->new, $level >= 3 ? 0:2); } ); DESCRIPTION Building a tree manually can be tedious: you have to connect the parent and the children nodes together: my $root = My::TreeNode->new(...); my $child1 = My::TreeNode->new(...); my $child2 = My::TreeNode->new(...); $root->children([$child1, $child2]); $child1->parent($root); $child2->parent($root); my $grandchild1 = My::Class->new(...); ... This module provides a convenience function to build a tree of objects in a single command. You supply a callback to create node and the function will connect the parent and children nodes for you. The callback is called with these arguments: ($parent, $level, $seniority) where $parent is the parent node object (or undef if creating the root node, which is the first time the callback is called), $level indicates the current depth of the tree (starting from 0 for the root node, then 1 for the root's children, then 2 for their children, and so on). You can use this argument to know where to stop creating nodes. $seniority indicates the position of the node against its sibling (0 means the node is the first child of its parent, 1 means the second, and so on). You can use this argument to perhaps customize the node according to its sibling order. The callback should return a list: ($node, $num_children) where $node is the created node object (the object can be of any class but it must respond to parent and children, see Role::TinyCommons::Tree::Node for more details on the requirement), $num_children is an integer that specifies the number of children that this node should have (0 means this node is to be a leaf node). The children will be created when the function calls the callback again later for each child node. FUNCTIONS create_tree_using_callback($cb) => obj SEE ALSO Other Tree::Create::* modules, e.g. Tree::Create::Size. Other ways to create tree: Tree::FromStruct, Tree::FromText, Tree::FromTextLines.