mirror of https://github.com/jab/bidict.git
57 lines
1.7 KiB
PHP
57 lines
1.7 KiB
PHP
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.. _overwritingbidict:
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``OverwritingBidict`` Recipe
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############################
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If you'd like
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:class:`OVERWRITE <bidict.DuplicationPolicy.OVERWRITE>`
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to be the default duplication policy for
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:func:`__setitem__() <bidict.bidict.__setitem__>` and
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:func:`update() <bidict.bidict.update>`,
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rather than always having to use
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:func:`forceput() <bidict.bidict.forceput>` and
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:func:`forceupdate() <bidict.bidict.forceupdate>`,
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you can use the following recipe::
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>>> from bidict import bidict, OVERWRITE
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>>> class OverwritingBidict(bidict):
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... on_dup_val = OVERWRITE
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>>> b = OverwritingBidict({'one': 1})
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>>> b['two'] = 1 # succeeds, no ValueDuplicationError
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>>> b
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OverwritingBidict({'two': 1})
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>>> b.update({'three': 1}) # ditto
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>>> b
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OverwritingBidict({'three': 1})
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As with
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:class:`bidict.bidict <bidict.bidict>`,
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``OverwritingBidict.put()`` and
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``OverwritingBidict.putall()``
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will still provide per-call overrides for duplication policies,
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and will both still default to raising for all duplication types
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unless you override those methods too.
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To make an overwriting *ordered* bidict,
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simply adapt this recipe to have the class inherit from
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:class:`bidict.OrderedBidict`.
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Beware of ``OVERWRITE``
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:::::::::::::::::::::::
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With a default :class:`OVERWRITE <bidict.DuplicationPolicy.OVERWRITE>` policy
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as in the ``OverwritingBidict`` recipe above,
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beware of the following potentially surprising behavior::
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>>> b = OverwritingBidict({'one': 1, 'two': 2})
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>>> b['one'] = 2
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>>> b
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OverwritingBidict({'one': 2})
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That is, setting an existing key to the value of a different existing item
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causes both existing items to be collapsed into a single item.
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