An object stores the change history of its attributes, the object can be use to store the hierarchies of different levels of configurations.

traced_obj.py

'''
An object stores the change history of its attributes,
the object can be use to store the hierarchies of different
levels of configurations.

Example
-------

# Set up config object
config = TracedObj()
config.server = "127.0.0.1"
config.port = 8080
config.remote = TracedObj()
config.remote.endpoint = "https://localhost:7997"

# Update the config somewhere else
config.server = "192.168.1.10"

# Get the history
config.get_history('server')

    [{'datetime': '2019-05-23 15:15:46.208067', 
      'filename': '<stdin>',
      'lineno': 1,
      'op': 'set',
      'value': '127.0.0.1'},
     {'datetime': '2019-05-23 15:15:53.288555',
      'filename': '<stdin>',
      'lineno': 1, 
      'op': 'set',
      'value': '192.168.1.10'}]

# Get the config hierarchy as as dict
config.as_dict()

    {'port': 8080, 
     'remote': {'endpoint': 'https://localhost:7997'},
     'server': '192.168.1.10'}
'''
import sys
import copy
import datetime


class TracedObj(object):
    def __init__(self):
        object.__setattr__(self, '_current', {})
        object.__setattr__(self, '_history', {})

    def update_trace_info(self, key, op, value=None):
        if key not in self._history:
            self._history[key] = []
        frame = sys._getframe(2)
        self._history[key].append({
            "op": op,
            "value": value,
            "datetime": str(datetime.datetime.now()),
            "filename": frame.f_code.co_filename,
            "lineno": frame.f_code.co_firstlineno
        })

    def __setattr__(self, key, value):
        self.update_trace_info(key, 'set', value=value)
        self._current[key] = value

    def __getattr__(self, key):
        return self._current[key]

    def __delattr__(self, key):
        self.update_trace_info(key, 'del')
        del self._current[key]

    def as_dict(self):
        ret = {}
        for k, v in self._current.items():
            if isinstance(v, TracedObj):
                ret[k] = v.as_dict()
            else:
                ret[k] = copy.copy(v)
        return ret

    def get_history(self, key):
        return self._history.get(key)