PEP: Configurable application

Overview of existing technologies

IPython

IPython Configuration Documentation

• based on traitlets (traits)
• auto command line generation
• easy to handle sub class configurations
• methods to generate and read config files
• need to explictly save configuration
• handle automatic namespaces based on class names : MyClass.Param1
• JSON or Python serialization
• support typing based on trait
• NO unique configuration (singleton)

Example of code

from IPython.config.configurable import Configurable
from IPython.config.application import Application
from IPython.utils.traitlets import (Bool, Unicode, List, Dict)


class Applet1(Configurable):
    name = Unicode(u'Guillaume', config=True, help="First name.")
    dry_run = Bool(True, config=True)

class MyApp(Application):
    classes = List([Applet1])
    config_file = Unicode(u'', config=True,
                   help="Load this config file")

    aliases = Dict({'name':'Applet1.name'})
    # config_file is reachable only with --MyApp.config_file=... or --help-all

    def initialize(self, argv=None):
        self.parse_command_line(argv)
        if self.config_file:
            self.load_config_file(self.config_file)
        self.foo = Applet1(config=self.config)

    def start(self):
        print "app.config:"
        print self.config

if __name__ == "__main__":
    app = MyApp()
    app.initialize()
    config_str = app.generate_config_file()
    app.start()

Default python file generated from this code :

# Configuration file for application.

c = get_config()

#------------------------------------------------------------------------------
# MyApp configuration
#------------------------------------------------------------------------------

# This is an application.

# MyApp will inherit config from: Application

# Set the log level by value or name.
# c.MyApp.log_level = 30

# The Logging format template
# c.MyApp.log_format = '[%(name)s]%(highlevel)s %(message)s'

# Load this config file
# c.MyApp.config_file = u''

# The date format used by logging formatters for %(asctime)s
# c.MyApp.log_datefmt = '%Y-%m-%d %H:%M:%S'

#------------------------------------------------------------------------------
# Applet1 configuration
#------------------------------------------------------------------------------

# First name.
# c.Applet1.name = u'Guillaume'

#
# c.Applet1.dry_run = True

ETS AppTools

ETS AppTools Preference Documentation

• based on traits & ConfigObj.
• handle configuration inheritance
• all parameters are stored as strings but types can be forced using a PreferenceHelper (HasTraits class) describing types for each parameter.

Example of inheritance :

>>> from apptools.preferences.preferences import Preferences
>>> pref = Preferences()
>>> pref.set('ui.color', 'black')
>>> pref.get('ui.editor.color', inherit=True)
'black'

Existing technology in OpenAlea

classes in openalea.core.settings :

Settings: singleton

Methods:  [
           'add_option', 'add_section', 'add_section_update_handler', 'configfile',
           'defaults', 'exists', 'get', 'getboolean', 'getfloat', 'getint', 'has_option',
           'has_section', 'instance', 'items', 'options', 'optionxform', 'read', 'readfp',
           'remove_option', 'remove_section', 'sections', 'set', 'write'
           ]