Are regular expressions worth the hassle?

Question

It strikes me that regular expressions are not understood well by the majority of developers. It also strikes me that for a lot of problems where regular expressions are use

Answer 1

Regular expressions are a domain-specific language: no generic programming language is quite as expressive or quite as efficient at doing what regular expressions do with string matching. The sheer size of the lump of code you will have to write in a standard programming language (even one with a good string library) will make it harder to maintain. It is also a good separation-of-concerns to make sure that the regular expression only does the matching. Having a code blob that basically does matching, but does something else in-between can produce some surprising bugs.

Also note that there are mechanisms to make regular expressions more readable. In Python you can enable verbose mode, which allows you to write things like this:

a = re.compile(r"""\d +  # the integral part
               \.    # the decimal point
               \d *  # some fractional digits""", re.X)

Another possibility is to build the regular expression up from strings, by line and comment each line, like this:

a = re.compile("\d+"  # the integral part
               "\."    # the decimal point
               "\d *"  # fraction  digits
               )

This is possible in different ways in most programming languages. My advice is to keep using regular expressions where appropriate, but treat them like you do other code. Write them as clear as possible, comment them and test them.