How to parse tags with '+' in python

Question

I get a "do not repeat anything" error when I try to compile this:

search = re.compile(r'([^a-zA-Z0-9])(%s)([^a-zA-Z0-9])' % '+test', re.I) 

The problem is the "+" sign. How do I handle this?

Answer 1

 re.compile(r'([^a-zA-Z0-9])(%s)([^a-zA-Z0-9])' % '\+test', re.I) 

A “+” is “repeat at least once” in regular expressions. It must follow something that is repeatable, or it must be escaped if you want to combine the literal "+".

This is better if you want to dynamically build your regular expression.

 re.compile(r'([^a-zA-Z0-9])(%s)([^a-zA-Z0-9])' % re.escape('+test'), re.I) 

Answer 2

Escape Plus:

 r'\+test' 

Plus has special meaning in regular expressions (the value "matches the previous one or more times"). Since it appears in your regex after an open pair, there is no “previous” to match again.