Fabric local commenter and uncommenter

fabfile.py

# -*- coding: utf-8 -*-
"""
Easy change settings with uncomment right string ang comment wrong.

Iterate over files in ``env.settings_files``, comment lines with
wrong marker and uncomment with right marker.

Usage
=====

>>> fab update_settings:mode=test

With this command all strings in ``/project_root/settings.py`` and
``/project_root/module/settings.py`` files with trailing '#-D' and 
'#-P' sequences will be commented and with '#-T' will be 
uncommented.
"""

from os import path
from fabric.api import env, local


env.settings_files = (
    path.join('projcet_root', 'settings.py'),
    path.join('projcet_root', 'module', 'settings.py'),
)
env.settings_versions = {
    'develop': '#-D',
    'test': '#-T',
    'production': '#-P',
}

def _commenter(c_type, filename, regex, use_sudo=False, char='#', backup='.bak'):
    """
    Work with comments in local files.
    """
    if use_sudo:
        sudoer = 'sudo '
    else:
        sudoer = ''

    if regex.startswith('^'):
        regex = regex[1:]

    if regex.endswith('$'):
        regex = regex[:-1]

    if c_type == 'comment':
        replacement = '%s ' % char
        char = '[^%s ]' % char
        regex = '(%s.+%s.*)' % (char, regex)
    else:
        replacement = ''
        regex = r'%s ?(.+%s.*)' % (char, regex)

    local(r"{sudo}sed -i{backup} -r -e 's/^([[:space:]]*){regex}$/"
        r"\1{replacement}\2/g' {filename}".format(**{
        'sudo': sudoer,
        'backup': backup,
        # 'char': char,
        'replacement': replacement,
        'regex': regex,
        'filename': filename,
    }))


def lcomment(*args, **kwargs):
    """
    Comment local files.
    """
    _commenter('comment', *args, **kwargs)


def luncomment(*args, **kwargs):
    """
    Uncomment local files.
    """
    _commenter('uncomment', *args, **kwargs)


def update_settings(mode):
    """
    Change files.
    """
    for filename in env.settings_files:
        for version in env.settings_versions:
            if mode == version:
                luncomment(filename, versions[version])
            elif:
                lcomment(filename, versions[version])