Python 正则表达式的命名约定？

Question

Is there an accepted naming convention for regular expressions in Python? Or if there's not, what are some suggestions on how to name them?

Usually I name them something like look_for_date or address_re but I've read several places that using a suffix like '_re' in a variable name isn't good. To me it seems like the regex needs something to indicate it's a regex, since if you named it just date or address , you wouldn't be able to do stuff like this, which seems intuitive:

date = date_re.match(text)

Answer 1

Compiled regular expressions are generally constants , so should have an UPPER_CASE_WITH_UNDERSCORES name per PEP 8 . I tend to name them for what they would match; to give an example from some code I wrote recently:

import re

VALID_CLOSURE_PATTERN = re.compile(r'''
    ^\d{2}    # starts with two digits 0-9
    [NY]{4}$  # followed by four Y/N characters
''', re.IGNORECASE + re.VERBOSE)


class RoadClosure(object):

    def __init__(self, ..., closure_pattern):
        """Initialise the new instance."""
        if not VALID_CLOSURE_PATTERN.match(closure_pattern):
            raise ValueError('invalid closure pattern: {!r}'.format(closure_pattern))
       ...

...

I think this makes it pretty clear what's going on, VALID_CLOSURE_PATTERN communicates "this describes what we would consider to be a valid closure pattern" and a line like:

if not VALID_CLOSURE_PATTERN.match(closure_pattern):

describes what it's actually doing in close to plain English. So in your case, you might write:

date = VALID_DATE.match(text)