Creating a Dependency Tree Using the Tree::DAG_Node Module and Postorder Transversal

hackdaddy has asked for the wisdom of the Perl Monks concerning the following question:

Hi. I am attempting to build a dependency tree using the Tree::DAG_Node module and then perform a postorder transversal of the tree. During my search for a solution, I ran across tadman's (Golf) Dependency List Prioritization post. This code appears to solve my dependency problem (no pub intended).

my @list = f(
     a => [ 'b', 'c' ],
     b => [ 'c', 'd' ],
     c => [ 'd' ],
     e => [ 'b', 'a' ],
     f => undef,
);


sub f {
  $h{$_}||=[]for map@$_,%h=@_;
  sub x {
    my$x=1;
    $x+=x($_)for@{@h{@_}||[]};
    $x
  }
  sort{x($a)<=>x$b}keys%h
}
[download]

However, having read through, in advance, gmax's tutorial A crash course on trees, I am itching to use the Tree::DAG_Node module to solve this problem. The stumbling block I am encountering is that I do not know how to take a data structure, such as tadman's in the code snippet above, and then programmatically create a Directed Acyclic Graph. With the tree constructed, I can then use the "walk_down" method with the callbackback option for a postorder scan.

Any assistance will be greatly appreciated. Thanks.

Comment on Creating a Dependency Tree Using the Tree::DAG_Node Module and Postorder Transversal Download Code

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Re: Creating a Dependency Tree Using the Tree::DAG_Node
by gmax (Abbot) on Jan 25, 2003 at 13:42 UTC

my %rules = (
     a => [ 'b', 'c' ],
     b => [ 'c', 'd' ],
     c => [ 'd' ],
     e => [ 'b', 'a' ],
     f => undef,
);
[download]

dependency
     /  \
   f     e
        | \
        |  a
        | / \
        b -- c
        |     \
        +----- d

my %rules = (
     a => [ 'b' ],
     b => [ 'c' ],
     c => [ 'd' ],
     e => [ 'a' ],
     f => undef,
);
[download]

my %rules = (
     a => [ 'b' ],
     b => [ 'c' ],
     c => [ 'd' ],
     e => [ 'b' ],
     f => undef,
);
[download]

    dependency
     /  \    \
   f     e    a
          \  / \ 
           b    c
                 \ 
                  d

S.M. Burke's article on trees

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