Given a regex that looks like this:

_regex_pattern = re.compile(r'["\')]}]+?(?:s+|(?=--)|$)', re.MULTILINE|re.UNICODE)

We can retrieve the flag with:

_regex_pattern.flags  # outputs "40"

And retrieve the pattern with:

_regex_pattern.pattern  # '["\')]}]+?(?:s+|(?=--)|$)'

If we want to store the regex into some kind of json, we will do something like:

_regex_json = {'pattern': _regex_pattern.pattern, 'flags': _regex_pattern.flags}

with open('regex.json', 'w') as fout:
    json.dump(_regex_json, fout)

But when we want to load the pattern, other than pickling, how do we convert the IntFlag to the regex flag?

with open('regex.json') as fin:
    _regex_json = json.load(fin)

_regex_pattern_loaded = re.compile(_regex_json['pattern'].encode('unicode_escape'), ???)

P/S: Pickling is not a viable solution for this task, since we’re literally going to compile something here, it’s not safe.