import configparser
import os

class DefaultOption(dict):
    def __init__(self, config, section, **kv):
        self._config = config
        self._section = section
        dict.__init__(self, **kv)
    def items(self):
        _items = []
        for option in self:
            if not self._config.has_option(self._section, option):
                _items.append((option, self[option]))
            else:
                value_in_config = self._config.get(self._section, option)
                _items.append((option, value_in_config))
        return _items

config = configparser.ConfigParser()
if os.environ.get('APP_ENV', 'development') == 'development':
    config.readfp(open('development.ini'))
    with open('development.ini') as f:
        print(f.read())
elif os.environ.get('APP_ENV') == 'production':
    config.readfp(open('production.ini'))

print(f"get config of {os.environ.get('APP_ENV')}")
print(config.get('DATABASE', 'host'))