CanMessage.py

import json
import logging
log = logging.getLogger(__name__)


class CanMessage(object):

 def __init__(self):
 self.last_revid = 0
 self.memory_file = 'last_revid.json'

 try:
 with open(self.memory_file) as file_handle:
 self.last_revid = json.load(file_handle)
 except Exception as ex:
 # TODO: empty file or no file at all, get the proper error
 pass
 log.debug("initialized with %s as the last revid", self.last_revid)

 def can_send(self, revid):
 return revid > self.last_revid

 def set_last_revid(self, revid):
 self.last_revid = revid

 def save(self):
 log.debug("saving")
 with open(self.memory_file, 'w') as file_handle:
 json.dump(self.last_revid, file_handle)


if __name__ == '__main__':
 can_message = CanMessage()
 if can_message.can_send(124):
 print('OK')
 can_message.set_last_revid(124)
 can_message.save()