Poor spot for a typo

[tn3270]

Have been using Perl/Regex quite a bit to convert one programming language into another. This has been going quite well, and I have been using the power of regex heavily. Today I was looking at a Perl book for some quirk of regexes, and one example looked really wrong. After puzzling a bit, I realized there was a typo in the regex syntax. That is just plain cruel; although regexes are very powerful, they tend to look like gibberish anyhow, even without a typographical error. I bet most copy editors do not review the regex syntax. Its a pretty hard problem, even a good technical reviewer would have a chore to check all the regexes in a book that had a lot of them (most Perl books).