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from .. import exceptions |
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from ..log import logger |
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4
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class AttributesHolder(object): |
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"""Stores attributes and provides read-only access to them.""" |
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__slots__ = ('_attributes') |
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_possible_attributes = None |
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def __init__(self, *args, **attributes): |
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attributes.update(dict(zip(self._possible_attributes, args))) |
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self._check_attributes(attributes) |
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self._parse_attributes(attributes) |
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def _check_attributes(self, attributes, extra=None): |
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"""Check if attributes given to the constructor can be used to |
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instanciate a valid node.""" |
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extra = extra or () |
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unknown_keys = set(attributes) - set(self._possible_attributes) - set(extra) |
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if unknown_keys: |
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logger.warning('%s got unknown attributes: %s' % |
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(self.__class__.__name__, unknown_keys)) |
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def __repr__(self): |
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return '<%s %r>' % (self.__class__.__name__, |
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{x:y for (x,y) in self._attributes.items()}) |
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def _parse_attributes(self, attributes): |
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self._attributes = attributes |
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def __eq__(self, other): |
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"""Tests equality with another AttributesHolder instance.""" |
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if isinstance(other, AttributesHolder): |
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return self._attributes == other._attributes |
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else: |
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return False |
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def __ne__(self, other): |
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return not (self == other) |
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def __hash__(self): |
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return hash(frozenset(self._attributes.items())) |
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def get(self, name, strict=True): |
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"""Get an attribute of the holder (read-only access).""" |
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if not isinstance(name, str) or name.startswith('_'): |
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raise AttributeError(self.__class__.__name__, name) |
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elif strict and name not in self._possible_attributes: |
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raise AttributeError('%s is not a valid attribute of %r.' % |
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(name, self)) |
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elif name in self._attributes: |
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return self._attributes[name] |
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else: |
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raise exceptions.AttributeNotProvided(name) |
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__getattr__ = __getitem__ = get |
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def __setattr__(self, name, value): |
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if name.startswith('_'): |
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super(AttributesHolder, self).__setattr__(name, value) |
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else: |
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raise TypeError('%s\'s attributes are not settable.' % |
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self.__class__.__name__) |
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def __delattr__(self, name): |
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if name.startswith('_'): |
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super(AttributesHolder, self).__delattr__(name, value) |
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else: |
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raise TypeError('%s\'s attributes are not settable.' % |
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self.__class__.__name__) |
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def has(self, name): |
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"""Check existence of an attribute.""" |
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return name in self._attributes |
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__hasattr__ = __contains__ = has |
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72
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ProjetPP /
PPP-datamodel-Python
