352 lines
13 KiB
Python
352 lines
13 KiB
Python
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# coding=utf-8
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"""Types for creating section definitions.
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A section definition consists of a subclass of ``StaticSection``, on which any
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number of subclasses of ``BaseValidated`` (a few common ones of which are
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available in this module) are assigned as attributes. These descriptors define
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how to read values from, and write values to, the config file.
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As an example, if one wanted to define the ``[spam]`` section as having an
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``eggs`` option, which contains a list of values, they could do this:
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>>> class SpamSection(StaticSection):
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... eggs = ListAttribute('eggs')
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...
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>>> SpamSection(config, 'spam')
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>>> print(config.spam.eggs)
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[]
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>>> config.spam.eggs = ['goose', 'turkey', 'duck', 'chicken', 'quail']
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>>> print(config.spam.eggs)
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['goose', 'turkey', 'duck', 'chicken', 'quail']
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>>> config.spam.eggs = 'herring'
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Traceback (most recent call last):
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...
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ValueError: ListAttribute value must be a list.
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"""
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from __future__ import unicode_literals, absolute_import, print_function, division
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import os.path
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import sys
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from tools import get_input
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try:
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import configparser
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except ImportError:
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import ConfigParser as configparser
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if sys.version_info.major >= 3:
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unicode = str
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basestring = (str, bytes)
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class NO_DEFAULT(object):
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"""A special value to indicate that there should be no default."""
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class StaticSection(object):
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"""A configuration section with parsed and validated settings.
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This class is intended to be subclassed with added ``ValidatedAttribute``\s.
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"""
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def __init__(self, config, section_name, validate=True):
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if not config.parser.has_section(section_name):
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config.parser.add_section(section_name)
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self._parent = config
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self._parser = config.parser
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self._section_name = section_name
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for value in dir(self):
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try:
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getattr(self, value)
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except ValueError as e:
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raise ValueError(
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'Invalid value for {}.{}: {}'.format(section_name, value,
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str(e))
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)
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except AttributeError:
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if validate:
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raise ValueError(
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'Missing required value for {}.{}'.format(section_name,
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value)
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)
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def configure_setting(self, name, prompt, default=NO_DEFAULT):
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"""Return a validated value for this attribute from the terminal.
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``prompt`` will be the docstring of the attribute if not given.
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If ``default`` is passed, it will be used if no value is given by the
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user. If it is not passed, the current value of the setting, or the
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default value if it's unset, will be used. Note that if ``default`` is
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passed, the current value of the setting will be ignored, even if it is
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not the attribute's default.
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"""
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clazz = getattr(self.__class__, name)
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if default is NO_DEFAULT:
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try:
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default = getattr(self, name)
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except AttributeError:
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pass
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except ValueError:
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print('The configured value for this option was invalid.')
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if clazz.default is not NO_DEFAULT:
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default = clazz.default
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while True:
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try:
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value = clazz.configure(prompt, default, self._parent, self._section_name)
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except ValueError as exc:
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print(exc)
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else:
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break
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setattr(self, name, value)
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class BaseValidated(object):
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"""The base type for a descriptor in a ``StaticSection``."""
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def __init__(self, name, default=None):
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"""
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``name`` is the name of the setting in the section.
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``default`` is the value to be returned if the setting is not set. If
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not given, AttributeError will be raised instead.
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"""
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self.name = name
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self.default = default
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def configure(self, prompt, default, parent, section_name):
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"""With the prompt and default, parse and return a value from terminal.
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"""
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if default is not NO_DEFAULT and default is not None:
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prompt = '{} [{}]'.format(prompt, default)
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value = get_input(prompt + ' ')
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if not value and default is NO_DEFAULT:
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raise ValueError("You must provide a value for this option.")
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value = value or default
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return self.parse(value)
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def serialize(self, value):
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"""Take some object, and return the string to be saved to the file.
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Must be implemented in subclasses.
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"""
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raise NotImplemented("Serialize method must be implemented in subclass")
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def parse(self, value):
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"""Take a string from the file, and return the appropriate object.
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Must be implemented in subclasses."""
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raise NotImplemented("Parse method must be implemented in subclass")
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def __get__(self, instance, owner=None):
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if instance is None:
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# If instance is None, we're getting from a section class, not an
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# instance of a session class. It makes the wizard code simpler
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# (and is really just more intuitive) to return the descriptor
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# instance here.
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return self
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if instance._parser.has_option(instance._section_name, self.name):
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value = instance._parser.get(instance._section_name, self.name)
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else:
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if self.default is not NO_DEFAULT:
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return self.default
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raise AttributeError(
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"Missing required value for {}.{}".format(
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instance._section_name, self.name
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)
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)
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return self.parse(value)
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def __set__(self, instance, value):
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if value is None:
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instance._parser.remove_option(instance._section_name, self.name)
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return
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value = self.serialize(value)
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instance._parser.set(instance._section_name, self.name, value)
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def __delete__(self, instance):
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instance._parser.remove_option(instance._section_name, self.name)
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def _parse_boolean(value):
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if value is True or value == 1:
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return value
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if isinstance(value, basestring):
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return value.lower() in ['1', 'yes', 'y', 'true', 'on']
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return bool(value)
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def _serialize_boolean(value):
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return 'true' if _parse_boolean(value) else 'false'
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class ValidatedAttribute(BaseValidated):
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def __init__(self, name, parse=None, serialize=None, default=None):
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"""A descriptor for settings in a ``StaticSection``
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``parse`` is the function to be used to read the string and create the
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appropriate object. If not given, return the string as-is.
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``serialize`` takes an object, and returns the value to be written to
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the file. If not given, defaults to ``unicode``.
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"""
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self.name = name
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if parse == bool:
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parse = _parse_boolean
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if not serialize or serialize == bool:
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serialize = _serialize_boolean
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self.parse = parse or self.parse
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self.serialize = serialize or self.serialize
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self.default = default
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def serialize(self, value):
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return unicode(value)
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def parse(self, value):
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return value
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def configure(self, prompt, default, parent, section_name):
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if self.parse == _parse_boolean:
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prompt += ' (y/n)'
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default = 'y' if default else 'n'
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return super(ValidatedAttribute, self).configure(prompt, default, parent, section_name)
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class ListAttribute(BaseValidated):
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"""A config attribute containing a list of string values.
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Values are saved to the file as a comma-separated list. It does not
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currently support commas within items in the list. By default, the spaces
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before and after each item are stripped; you can override this by passing
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``strip=False``."""
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def __init__(self, name, strip=True, default=None):
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default = default or []
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super(ListAttribute, self).__init__(name, default=default)
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self.strip = strip
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def parse(self, value):
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value = value.split(',')
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if self.strip:
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return [v.strip() for v in value]
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else:
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return value
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def serialize(self, value):
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if not isinstance(value, (list, set)):
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raise ValueError('ListAttribute value must be a list.')
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return ','.join(value)
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def configure(self, prompt, default, parent, section_name):
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each_prompt = '?'
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if isinstance(prompt, tuple):
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each_prompt = prompt[1]
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prompt = prompt[0]
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if default is not NO_DEFAULT:
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default = ','.join(default)
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prompt = '{} [{}]'.format(prompt, default)
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else:
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default = ''
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print(prompt)
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values = []
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value = get_input(each_prompt + ' ') or default
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while value:
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values.append(value)
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value = get_input(each_prompt + ' ')
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return self.parse(','.join(values))
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class ChoiceAttribute(BaseValidated):
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"""A config attribute which must be one of a set group of options.
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Currently, the choices can only be strings."""
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def __init__(self, name, choices, default=None):
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super(ChoiceAttribute, self).__init__(name, default=default)
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self.choices = choices
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def parse(self, value):
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if value in self.choices:
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return value
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else:
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raise ValueError('Value must be in {}'.format(self.choices))
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def serialize(self, value):
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if value in self.choices:
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return value
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else:
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raise ValueError('Value must be in {}'.format(self.choices))
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class FilenameAttribute(BaseValidated):
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"""A config attribute which must be a file or directory."""
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def __init__(self, name, relative=True, directory=False, default=None):
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"""
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``relative`` is whether the path should be relative to the location
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of the config file (absolute paths will still be absolute). If
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``directory`` is True, the path must indicate a directory, rather than
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a file.
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"""
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super(FilenameAttribute, self).__init__(name, default=default)
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self.relative = relative
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self.directory = directory
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def __get__(self, instance, owner=None):
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if instance is None:
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return self
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if instance._parser.has_option(instance._section_name, self.name):
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value = instance._parser.get(instance._section_name, self.name)
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else:
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if self.default is not NO_DEFAULT:
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value = self.default
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else:
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raise AttributeError(
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"Missing required value for {}.{}".format(
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instance._section_name, self.name
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)
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)
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main_config = instance._parent
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this_section = getattr(main_config, instance._section_name)
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return self.parse(main_config, this_section, value)
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def __set__(self, instance, value):
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main_config = instance._parent
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this_section = getattr(main_config, instance._section_name)
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value = self.serialize(main_config, this_section, value)
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instance._parser.set(instance._section_name, self.name, value)
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def configure(self, prompt, default, parent, section_name):
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"""With the prompt and default, parse and return a value from terminal.
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"""
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if default is not NO_DEFAULT and default is not None:
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prompt = '{} [{}]'.format(prompt, default)
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value = get_input(prompt + ' ')
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if not value and default is NO_DEFAULT:
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raise ValueError("You must provide a value for this option.")
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value = value or default
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return self.parse(parent, section_name, value)
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def parse(self, main_config, this_section, value):
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if value is None:
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return
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value = os.path.expanduser(value)
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if not os.path.isabs(value):
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if not self.relative:
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raise ValueError("Value must be an absolute path.")
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value = os.path.join(main_config.homedir, value)
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if self.directory and not os.path.isdir(value):
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try:
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os.makedirs(value)
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except OSError:
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raise ValueError(
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"Value must be an existing or creatable directory.")
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if not self.directory and not os.path.isfile(value):
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try:
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open(value, 'w').close()
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except OSError:
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raise ValueError("Value must be an existant or creatable file.")
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return value
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def serialize(self, main_config, this_section, value):
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self.parse(main_config, this_section, value)
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return value # So that it's still relative
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