I would imagine that your line-based approach will - once you exclude the standard-for-your-coding-style lines above - show you most of your copy-and-paste.

I'd actually start from the other end, looking for infrequently-occuring-but-nonunique lines. A line which is used in exactly 2 or 3 places is more likely to be part of a block of cut and paste than one used in 100.

When you are refactoring, a nice option you have in perl is to make use of first class functions/closures/anonymous subs.

This allows you to have more "fuzzy matching" between blocks of similar-but-not-identical code. You can pull out the shared boilerplate as a new method/sub and pass into it a closure which does the 'bit which is different for each occurence'.

It's a lightweight alternative to putting together an inheritance hierarchy to share code, which you may see in design patterns etc. For example: 

sub print_tree
{
  my $tree = shift;
  print_tree($tree->left);
  print $tree->value;
  print_tree($tree->right);
}

sub sum_tree
{
  my $tree = shift;
  return sum_tree($tree->left)
         + $tree->node
         + sum_tree($tree->right);
}

[download]
could become (sorry, this is untested - also, this exact example might be better as a Tree class, which probably already exists in CPAN, etc etc., but I hope the point survives): 

sub walk_tree
{
  my $tree = shift;
  my $per_node = shift;
  walk_tree($tree->left);
  $per_node->($tree->node);
  walk_tree($tree->right);
}

sub print_tree
{
  my $tree = shift;
  walk_tree($tree, sub { print $_[0]; });
}

sub sum_tree
{
  my $tree = shift;
  my $total = 0;
  walk_tree($tree, sub { $total += $_[0]; });
  return $total;
}

[download]

In reply to Re: Refactoring tools for copy/paste jobs by jbert
in thread Refactoring tools for copy/paste jobs by rhesa

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