Use of logging module to track TODOs


Jordi Riera

Hey list,

I always have issues with TODOs as they stay in the code and most of time forgot.
On that, I tried to find a way to track them and to be able to output them automatically. Automatically is a key as if devs have to do it manually it won't be done.

While I was checking the logging module and it features I thought about a little hack on it to use it to check files and output TODOs.
Logging check files and can have different channels for each level.
_Well, it needs to write another way the TODO as it will be now a new logging level and TODO would be wrote as logger.todo('Comment here')_

Here is my code:
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# pylint: disable=W0511
# disabled the warning about TODOs
""" Adding a new level to the logging.
the new level will help to trace the TODOs in files.
import logging
import os
import sys
import json
# setting the new level in logging module.
new_level = (logging.DEBUG + 1, 'TODO')
logging.TODO = new_level[0]

class DictFormatter(logging.Formatter):
""" Formatter emitting data in the form of a dictionnary.

dict Pattern:
{ {
record.lineno: {
'message': record.getMessage(),
'created': self.formatTime(record, self.datefmt),
'funcName': record.funcName,
def format(self, record):
""" Save the data in the json file and return the return
of the parent class.
message = record.getMessage()

if record.exc_info:
# Cache the traceback text to avoid converting it multiple times
# (it's constant anyway)
if not record.exc_text:
record.exc_text = self.formatException(record.exc_info)

if record.exc_text:
message = record.exc_text
except UnicodeError:
# Sometimes filenames have non-ASCII chars, which can lead
# to errors when s is Unicode and record.exc_text is str
# See issue 8924.
# We also use replace for when there are multiple
# encodings, e.g. UTF-8 for the filesystem and latin-1
# for a script. See issue 13232.
message = record.exc_text.decode(

return {
unicode(record.lineno): {
u'message': unicode(message),
u'created': unicode(self.formatTime(record, self.datefmt)),
u'funcName': unicode(record.funcName),

class SpecificJsonFileHandler(logging.FileHandler):
""" Specific FileHandler emitting a specific level of message.

:attribute level_message: logging level of message to consider. (int)
def __init__(self, level_message, *args, **kwargs):
super(SpecificJsonFileHandler, self).__init__(*args, **kwargs)
self.__level_message = level_message

# To know if it is the first time the handler emit.
# It meant to know if we need to reset the data for this file in the json file.
self.__first_emit = True

def emit(self, record):
""" Only save in a json for the specific level of message. Skip all other messages."""
if record.levelno == self.__level_message:
with open(self.baseFilename, 'r') as json_file:
data = json.load(json_file)
except ValueError:
data = {}

# Test if it is the fist time the instance will emit for the logger.
# At this point, the data from the logger is reset to avoid to keep
# cancelled/resolved todos.
if self.__first_emit:
data[] = {}
self.__first_emit = False


with open(self.baseFilename, 'w') as json_file:
json.dump(data, json_file, sort_keys=True, indent=4)

class TodoLogger(logging.getLoggerClass()):
""" Logger accepting the Todo parameter."""
__default_filename = 'log.log'

def __init__(self, *args, **kwargs):
super(TodoLogger, self).__init__(*args, **kwargs)
self.__handler = SpecificJsonFileHandler(
kwargs.get('todo_filename', self.__default_filename),


def todo(self, message, *args, **kwargs):
""" Log 'msg % args' with severity 'TODO'.

To pass exception information, use the keyword argument exc_info with
a true value, e.g.

logger.debug("Houston, we have a %s", "thorny problem", exc_info=1)

If the dev environment is detected and even the level is not enabled,
the log will be saved in the json file to keep the file up to date.
# Need this test or the message of TODOS will be always displayed.
if self.isEnabledFor(logging.TODO):
self._log(logging.TODO, message, args, **kwargs)
# If the logger is used by a developer, even if it is not enabled
# we save the todos in the json file.
elif self.isDevEnv():
# We will trick the system here to keep the engine running
# and so stay compatible with any update of logging module.
# Basically, we will make the system believing there in only
# the handler linked to the JsonFormater to run.
# So we save the list of all the handler registered to the logger.
handlers = self.handlers
# we register the handler we are interested in.
self.handlers = [self.__handler]
# Run the system as nothing particular happened.
self._log(logging.TODO, message, args, **kwargs)
# then we register back all the handlers.
self.handlers = handlers

# pylint: disable=C0103
# Disable the warning about the name convention. I am following the name
# convention of the module.
def isDevEnv():
""" Test to detect if the environment is a development environment.

:rtype: bool
return 'DEVELOPMENT' in os.environ


The code is a first try. It needs updates and surely have weaknesses. I plan to have a JsonToMd translator pre-push hook. So each time a push is sent, a will be update with the new version of the json.
fixme, note etc. might be easy added if needed.
I would be interested to know your point of view on this.

How do you do with your TODOs?


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