mirror of https://github.com/jab/bidict.git
68 lines
1.9 KiB
Plaintext
68 lines
1.9 KiB
Plaintext
# Copyright 2018 Joshua Bronson. All Rights Reserved.
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#
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# This Source Code Form is subject to the terms of the Mozilla Public
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# License, v. 2.0. If a copy of the MPL was not distributed with this
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# file, You can obtain one at http://mozilla.org/MPL/2.0/.
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Test script for pairs::
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>>> from bidict import pairs
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Abstracts differences between Python 2 and 3::
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>>> it = pairs({1: 2})
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>>> next(it)
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(1, 2)
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>>> next(it)
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Traceback (most recent call last):
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...
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StopIteration
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Accepts zero or one positional argument which it first tries iterating over
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as a mapping (as above), and if that fails, falls back to iterating over as
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a sequence, yielding items two at a time::
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>>> it = pairs([(1, 2), (3, 4)])
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>>> next(it)
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(1, 2)
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>>> next(it)
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(3, 4)
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>>> next(it)
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Traceback (most recent call last):
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...
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StopIteration
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>>> list(pairs())
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[]
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Mappings may also be passed as keyword arguments, which will be yielded
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after any passed via positional argument::
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>>> list(sorted(pairs(a=1, b=2)))
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[('a', 1), ('b', 2)]
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>>> list(sorted(pairs({'a': 1}, b=2, c=3)))
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[('a', 1), ('b', 2), ('c', 3)]
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>>> list(sorted(pairs([('a', 1)], b=2, c=3)))
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[('a', 1), ('b', 2), ('c', 3)]
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In other words, this is like a generator analog of the dict constructor.
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If any mappings from a sequence or keyword argument repeat an
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earlier mapping in the positional argument, repeat mappings will still
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be yielded, whereas with dict the last repeat clobbers earlier ones::
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>>> dict([('a', 1), ('a', 2)])
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{'a': 2}
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>>> list(pairs([('a', 1), ('a', 2)]))
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[('a', 1), ('a', 2)]
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>>> dict([('a', 1), ('a', 2)], a=3)
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{'a': 3}
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>>> list(pairs([('a', 1), ('a', 2)], a=3))
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[('a', 1), ('a', 2), ('a', 3)]
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Invalid calls result in errors::
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>>> list(pairs(1, 2))
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Traceback (most recent call last):
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...
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TypeError: Pass at most 1 positional argument (got 2)
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