114 lines
3.5 KiB
Python
114 lines
3.5 KiB
Python
#!/usr/bin/env python2
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# -*- coding: utf-8 -*-
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"""Combined config file and argument parser."""
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try:
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from ConfigParser import SafeConfigParser as ConfigParser, NoOptionError
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except ImportError:
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from configparser import ConfigParser, NoOptionError
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from argparse import ArgumentParser
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import sys
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class _Dummy(object):
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"""Placeholder for config sections."""
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pass
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class ComboParser(object):
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"""Parse configuration from INI file and command-line arguments.
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Command-line arguments override INI file values.
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"""
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def __init__(self, ini):
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self.items = []
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self.cparser = ConfigParser()
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self.aparser = ArgumentParser()
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self.ini = ini
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self.loaded = False
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self.args = None
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def add_item(self, section, name, type, default, desc, required):
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"""Add a configuration item."""
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def str2bool(val):
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return val.lower() in ('true', '1', 'yes')
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self.items.append({
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'section': section,
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'name': name,
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'type': type,
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'default': default,
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'required': required,
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})
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self.aparser.add_argument(
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'--%s.%s' % (section, name),
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help='%s (default: %s)' % (desc, default),
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type=type if type is not bool else str2bool,
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default=None,
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required=False
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)
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def load(self):
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"""Load configuration from file and command-line."""
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if self.loaded:
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return
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self.loaded = True
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try:
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self.cparser.read(self.ini)
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except Exception:
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pass # Config file missing or unreadable, use defaults
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self.args = self.aparser.parse_args()
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for item in self.items:
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section = item['section']
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name = item['name']
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# Ensure section object exists
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if not hasattr(self, section):
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setattr(self, section, _Dummy())
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obj = getattr(self, section)
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# Start with default value
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value = item['default']
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found = False
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# Try to read from config file
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try:
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if item['type'] is bool:
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value = self.cparser.getboolean(section, name)
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elif item['type'] is float:
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value = self.cparser.getfloat(section, name)
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elif item['type'] is int:
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value = self.cparser.getint(section, name)
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elif item['type'] is str:
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value = self.cparser.get(section, name)
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found = True
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except NoOptionError:
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pass
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# Command-line overrides config file
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arg_name = '%s.%s' % (section, name)
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arg_value = getattr(self.args, arg_name, None)
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if arg_value is not None:
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value = arg_value
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found = True
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# Handle missing required items
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if not found:
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if item['required']:
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sys.stderr.write(
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'error: required config item "%s" not found in section "%s" of "%s"\n'
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% (name, section, self.ini)
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)
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sys.exit(1)
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else:
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sys.stderr.write(
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'warning: assigned default value of "%s" to "%s.%s"\n'
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% (item['default'], section, name)
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)
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setattr(obj, name, value)
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