bpo-33609: Document dict insertion order guarantee as of 3.7 (GH-7093) · python/cpython@8585ec9 (original) (raw)

``` @@ -4229,6 +4229,29 @@ pairs within braces, for example: {'jack': 4098, 'sjoerd': 4127} or ``{4098:


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```  value)`` pairs. Order comparisons ('<', '<=', '>=', '>') raise

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`` :exc:TypeError.

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Dict preserves insertion order. Note that updating key doesn't affects the

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order. On the other hand, keys added after deletion are inserted to the

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last. ::

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+

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d = {"one": 1, "two": 2, "three": 3, "four": 4}

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d

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{'one': 1, 'two': 2, 'three': 3, 'four': 4}

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list(d)

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['one', 'two', 'three', 'four']

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list(d.values())

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[1, 2, 3, 4]

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d["one"] = 42

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d

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{'one': 42, 'two': 2, 'three': 3, 'four': 4}

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del d["two"]

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d["two"] = None

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d

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{'one': 42, 'three': 3, 'four': 4, 'two': None}

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+

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.. versionchanged:: 3.7

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Dict order is guaranteed to be insertion order. This behavior was

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implementation detail of CPython from 3.6.

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+

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`.. seealso::

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`` :class:types.MappingProxyType can be used to create a read-only view

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`` of a :class:dict.