You can use a variable to specify just the method, not arguments. What you could do have an array of arrays and call thusly:

my @commands = (
                 [ 'add_node', 'W1' ],
                 [ 'add_node', 'W2' ],
                 [ 'add_edge', 'W1', 'W2' ],
                );

use GraphViz; 
my $g = GraphViz->new(); 
foreach my $cur ( @commands ) {
  my $method = shift @{$cur};
  $g->$method( @{ $cur } );
}
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