Composed Regular Expressions - breaking a regex down into a readable form

Question

I was reading an article put together by Martin Fowler regarding Composed Regular Expressions. This is where you might take code such as this:

const string patt         


        

Answer 1

Yes, absolutely. Regexes are powerful, but because of their terse syntax, extremely unreadable. When I read a comment such as "this matches an URI", that doesn't actually help me figure out how it does that, and where I should look to (for example) fix a bug where it doesn't match some obscure corner case in query string properly. Regex is code; document it as you'd document a function. If it's short and (reasonably) clear, a single comment for the entire regex is fine. If it's complicated, clearly highlight and comment individual parts. If it's really complex, split it into several regexes.