ruamel.appconfig 0.2

create and read configuration dir/file set argparse (sub)parser defaults from config

This module provides a way to easily add a config directory and file to an application. The config directory can be used for additional user specific data files.:

.. example output clean.py

It uses ruamel.yaml for reading and writing the configuration files, as this library preserves any comments added (which pythons own ConfigParser discards).

The basic invocation is:

from __future__ import print_function

import sys

from ruamel.appconfig import AppConfig

def to_stdout(*args):
    sys.stdout.write(' '.join(args))

ac = AppConfig(
    'appconfigbasic',  # name of config diretory, normally the application name
    warning=to_stdout,
)

Resulting in:

created directory /home/a114/.config/appconfigbasic

By default (on Linux) the config directory is created under ~/.config, and the default config file would be ~/.config/appconfigbasic/appconfigbasic.ini (the appconfigbasic being the value passed to AppConfig(). Before that it is tested if that file already exists, or whether ~/.appconfigbasic/appconfigbasic.ini or ~/.appconfigbasic.ini exists.

On windows the config directory is to be $APPDATA/appconfigbasic

Interaction with argparse

AppConfig() has additional options to interact with argparse argument parsing:

• it is able to fill in the defaults for application options (including those options for subparsers).

• it can add a --config option to allow the user to specify an alternative path for the config file.

• it can add a --save-defaults with which the user can save values for options specified on the commandline, to the config file. Global options are stored in the [global] section of the configuration file, options for subparsers in sections with the suparser name.

Adding --config

To get this option added, pass in the parser and set the filename parameter to the AppConfig.check attribute:

from __future__ import print_function

from argparse import ArgumentParser
from ruamel.appconfig import AppConfig

parser = ArgumentParser()

ac = AppConfig(
    'appconfigconfig',
    parser=parser,  # needed to set new options
    filename=AppConfig.check,  # sets --config option
)

parser.parse_args(['--help'])

Resulting in:

usage: addconfig.py [-h] [--config FILE]

optional arguments:
  -h, --help     show this help message and exit
  --config FILE  set FILE as configuration file
                 [~/.config/appconfigconfig/appconfigconfig.ini]

Setting defaults and adding --save-defaults

To add the saving the defaults to the config file:

from __future__ import print_function

from argparse import ArgumentParser
from ruamel.appconfig import AppConfig

parser = ArgumentParser()

parser.add_argument('--delete', '-d', default='bla',
                    help='delete a file (default: %(default)s)')
parser.add_argument('--owner', default='itsme',
                    help='set owner (default: %(default)s)')
parser.add_argument('--force', action='store_true',
                    help='force action (default: %(default)s)')
ac = AppConfig(
    'addconfigsave',
    parser=parser,  # needed to set new options
    filename=AppConfig.check,  # sets --config option
    add_save=True,  # add save option
)
ac.set_defaults()  # set the ArgumentParser() defaults
# and save to config file
args = ac.parse_args(['--delete', 'two', '--save-defaults'])

with open(ac.get_file_name()) as fp:
    print(fp.read())

Resulting in:

[global]
delete = two
owner = itsme
force = False

Interaction with ruamel.std.argparse decorators

Since the ruamel.std.argparse decorator is a wrapper around normal argparse usage, adding AppConfig() is easy:

from __future__ import print_function

import sys
import os

from ruamel.std.argparse import ProgramBase, option, sub_parser, version, \
    SmartFormatter


class TestCmd(ProgramBase):
    def __init__(self):
        super(TestCmd, self).__init__(
            formatter_class=SmartFormatter
        )

    # you can put these on __init__, but subclassing TestCmd
    # will cause that to break
    @option('--quiet', '-q', help='suppress verbosity', action='store_true',
            global_option=True)
    @version('version: 1.2.3')
    def _pb_init(self):
        # special name for which attribs are included in help
        pass

    def run(self):
        if self._args.func:
            return self._args.func()

    def parse_args(self, *args):
        from ruamel.appconfig import AppConfig
        app = 'addconfigcomplex'
        # pre populate config file
        with open(os.path.expanduser(
            '~/.config/{}/{}.ini'.format(app, app)), 'w') as fp:
            fp.write('[readit]\nname=XYZ\n')
        self._config = AppConfig(
            app,
            parser=self._parser,  # self._parser set by ProgramBase
            filename=AppConfig.check,  # sets --config option
            add_save=True,  # add save option
        )
        self._config.set_defaults()
        self._parse_args(*args)

    @sub_parser(help='specific help for readit')
    @option('--name', default='abc',
            help='help for name (default: %(default)s)')
    def readit(self):
        print('calling readit')

    @sub_parser('writeit', help='help for writeit')
    @option('--target')
    def other_name(self):
        print('calling writeit')


n = TestCmd()
n.parse_args(['readit', '--help'])  # normaly no parameters -> sys.argv
n.run()  # never reached

With output (please note the XYZ as defaults):

usage: complex.py readit [-h] [--name NAME] [--quiet] [--save-defaults]

optional arguments:
  -h, --help       show this help message and exit
  --name NAME      help for name (default: XYZ)
  --quiet, -q      suppress verbosity
  --save-defaults  save option values as defaults to config file