configsimple

Configure a command/tall and its components via command line options, config files and environment variables.

This builds on the ConfigArgParse package, but instead of a replacement for the ArgumentParser class, provides its own class ConfigSimple which can be used to define the possible settings using add_argument and after parsing the settings, to retrieve the setting values.

Each ConfigSimple instance represents either the "top level" settings (similar to ArgumentParser usually for tools and programs) or a component setting that belongs to a top level setting instance.

The configsimple package provides a default top level settings singleton, configsimple.config.

Here is an example of how to define the settings for the toplevel and two components, where the toplevel selects the component to get used:

example/example1.py:

from configsimple import config, ConfigSimple, flag


class Component1:
    def __init__(self):
        myconf = ConfigSimple(component="comp1")
        config.add_config(myconf)  # always immediately add to top config!
        myconf.add_argument("--foo", default="22", type=int, help="The FOO setting!")
        myconf.add_argument("--bar", type=flag)
        myconf.parse_args()
        foo = myconf.get("foo")


class Component2:
    def __init__(self):
        myconf = ConfigSimple(component="comp2")
        config.add_config(myconf)
        myconf.add_argument("--foo", default="xyz", type=str, help="The FOO setting, but a different one!")
        myconf.parse_args()
        foo = myconf.get("foo")


if __name__ == "__main__":
    config.add_argument("--bar", help="The BAR setting")
    config.add_argument("--foo", help="The toplevel FOO setting")
    config.add_argument("--comp", type=int, choices=[1, 2], required=True,  help="Component number")
    config.add_argument("pos1")  # only the top config may have positional arguments
    config.parse_args()
    print("Toplevel foo is {}".format(config.get("foo")))
    compclass = [Component1, Component2][config.get("comp")-1]
    comp = compclass()
    print("Get the global comp1.foo: {}".format(config.get("comp1.foo")))
    print("Get the global comp2.foo: {}".format(config.get("comp2.foo")))
    print("Get the global comp1.bar: {}".format(config.get("comp1.bar")))
    print("Top positional parameter pos1: {}".format(config.get("pos1")))

One way to run this:

$ python examples/example1.py --comp 1 1 --comp1.foo 2
Toplevel foo is None
Component1 foo is 2
Get the global comp1.foo: 2
Get the global comp2.foo: None
Get the global comp1.bar: None
Top positional parameter pos1: 1

This selects component comp1 to get initialised which in turn will set the comp1.foo parameter. Note that the positional parameter "pos1" MUST be specified before any component arguments!

In order to get usage information for the component comp1 settings, we cann run:

$ python examples/example1.py --comp 1 x --comp1.help
Toplevel foo is None
usage: example1.py [--comp1.help] [--comp1.config_file COMP1.CONFIG_FILE]
                   [--comp1.save_config_file CONFIG_OUTPUT_PATH]
                   [--comp1.foo COMP1.FOO] [--comp1.bar COMP1.BAR]

optional arguments:
  --comp1.help          Show help for the 'comp1' component
  --comp1.config_file COMP1.CONFIG_FILE
                        Specify a file from which to load settings for
                        component 'comp1'
  --comp1.save_config_file CONFIG_OUTPUT_PATH
                        Specify a file to which to save specified settings.
  --comp1.foo COMP1.FOO
                        The FOO setting!
  --comp1.bar COMP1.BAR

This shows the help information as soon as the parameters are getting parsed in component comp1. For this to work, the required top level arguments have to be provided.

NOTE

This package is meant to build on and depend on ConfigArgParse package, but because of a problem in that code, a slightly modified version of configargparse.py is currently directly included.