ruamel.appconfig 0.5.5

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 config file to an application. The config directory can be used for additional user specific data files.

By default 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,
)

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 directory, normally the application name
    warning=to_stdout,
)

Resulting in:

created directory /home/a114/.config/appconfigbasic

By default (on Linux/macOS) 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 outputs (please note the XYZ as default, because of the config file being written before the AppConfig instantiation):

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