Parses timezone strings in ISO 8601 format to datetime.tzinfo objects

timezone.py

import datetime
import re
import logging

class TimeZone( datetime.tzinfo ):
    
    def __init__( self, offset ):
        # expects offset in ISO 8601 format e.g '+00:00', '+0000', 'Z'
        # see https://en.wikipedia.org/wiki/ISO_8601#Time_zone_designators
        
        # default offset
        offs = datetime.timedelta(0)

        # parse the string in a try / except block in case regex parsing fails
        try:
            if offs != 'Z':
                m = re.match( r'([+-]*)(\d\d)(:*)(\d\d)', offset )
                sign = m.group(1)
                offs = datetime.timedelta(
                    hours=int(m.group(2)),
                    minutes=int(m.group(4))
                )
                if sign == "-":
                    offs = datetime.timedelta(0) - offs
        except Exception as e:
            logging.exception( e )
        
        self._offset = offs
        self._name = offset
    
    def utcoffset(self, dt):
        return self._offset

    def tzname(self, dt):
        return self._name

    def dst(self, dt):
        return datetime.timedelta(0)