I am using Emacs and perltidy by adding the lines

# (compile (concat "perltidy " (buffer-name)) nil)
# (ediff-files (concat (buffer-name) ".tdy") (buffer-name))
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Putting the cursor at the end of the added lines and entering control-X, control-E will execute perltidy and activate the ediff-files function in Emacs. Then I can select which part of my script I want to be changed.