Local Effects

Here's the idea:

        { my $temporary = LocalChdir->chdir_to($DIR);
          ...
        }

When control exits the block, $temporary will be destroyed
We can rig up LocalChdir::DESTROY to move back to the old directory

        package LocalChdir;
        use Cwd;

        sub chdir_to {
          my ($package, $new_dir) = @_;
          my $old_dir = cwd();
          return unless chdir($new_dir);
          bless { DIR => $old_dir } => $package;
        }

        sub DESTROY {
          my $dir = $_[0]{DIR};
          chdir($dir) 
            or croak("Couldn't return to '$dir' on block exit: $!");
        }