The first tip is okay, but the latter 4 are just horrible. Any decent language will have libraries for parsing HTML or e-mails addresses. A regex is sure to come up short and be very fragile.
I once had to maintain some screen-scraping code that was written in Python using regular expressions. By the time I inherited it, half of the functionality no longer worked. It would have been much better off using a library like BeautifulSoup, both in terms of development time and maintainability.
BeautifulSoup alone takes care of REs 2 and 3, and there are standard libraries in Python that take care of 4 and 5. Why reinvent (less robustly, I might add) the wheel when a simple API already exists in many languages?
I once had to maintain some screen-scraping code that was written in Python using regular expressions. By the time I inherited it, half of the functionality no longer worked. It would have been much better off using a library like BeautifulSoup, both in terms of development time and maintainability.
BeautifulSoup alone takes care of REs 2 and 3, and there are standard libraries in Python that take care of 4 and 5. Why reinvent (less robustly, I might add) the wheel when a simple API already exists in many languages?