How do I do line continuation with a long regex? [duplicate]

Question

I have a long regex that I want to continue on to the next line, but everything I've tried gives me either an EOL or breaks the regex. I have already continued the line once within the parenthesis, and have read How can I do a line break (line continuation)? among other things.

Working, but still too long:

REGEX = re.compile(
            r'\d\s+\d+\s+([A-Z0-9-]+)\s+([0-9]+.\d\(\d\)[A-Z0-9]+)\s+([a-zA-Z\d-]+)')

Wrong:

REGEX = re.compile(
            r'\d\s+\d+\s+([A-Z0-9-]+)\s+([0-9]+.\d\(\d\)[A-Z0-9]+
            )\s+([a-zA-Z\d-]+)')

SyntaxError: EOL while scanning string literal


REGEX = re.compile(
            r'\d\s+\d+\s+([A-Z0-9-]+)\s+([0-9]+.\d\(\d\
                )[A-Z0-9]+)\s+([a-zA-Z\d-]+)')
    
sre_constants.error: unbalanced parenthesis


REGEX = re.compile(
            r'\d\s+\d+\s+([A-Z0-9-]+)\s+( \
            [0-9]+.\d\(\d\)[A-Z0-9]+)\s+([a-zA-Z\d-]+)')

regex no longer works


REGEX = (re.compile(
            r'\d\s+\d+\s+([A-Z0-9-]+)\s+(
            [0-9]+.\d\(\d\)[A-Z0-9]+)\s+([a-zA-Z\d-]+)'))

SyntaxError: EOL while scanning string literal

I have been able to shorten my regex so that this is no longer an issue, but I'm now interested to know how I might do line continuation with a long regex?

Answer 1

If you use the re.VERBOSE flag, you can split your regular expression up as much as you like to make it more readable:

pattern = r"""
    \d\s+
    \d+\s+
    ([A-Z0-9-]+)\s+
    ([0-9]+.\d\(\d\)[A-Z0-9]+)\s+
    ([a-zA-Z\d-]+)"""

REGEX = re.compile(pattern, re.VERBOSE)

This approach is explained in the excellent "Dive Into Python" book.
See "Verbose Regular Expressions".