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Fix issue9132 - Documentation for comparing dictionaries is out of date

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Senthil Kumaran 2010-07-14 20:30:02 +00:00
parent 04f31b8ae6
commit 0736767fdf
1 changed files with 3 additions and 12 deletions
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15
Doc/reference/expressions.rst
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@ -1031,9 +1031,9 @@ Comparison of objects of the same type depends on the type:
``x <= y``. If the corresponding element does not exist, the shorter ``x <= y``. If the corresponding element does not exist, the shorter
sequence is ordered first (for example, ``[1,2] < [1,2,3]``). sequence is ordered first (for example, ``[1,2] < [1,2,3]``).
* Mappings (dictionaries) compare equal if and only if their sorted ``(key, * Mappings (dictionaries) compare equal if and only if they have the same
value)`` lists compare equal. [#]_ Outcomes other than equality are resolved ``(key, value)`` pairs. Order comparisons ``('<', '<=', '>=', '>')``
consistently, but are not otherwise defined. [#]_ raise :exc:`TypeError`.
* Sets and frozensets define comparison operators to mean subset and superset * Sets and frozensets define comparison operators to mean subset and superset
tests. Those relations do not define total orderings (the two sets ``{1,2}`` tests. Those relations do not define total orderings (the two sets ``{1,2}``
@ -1330,15 +1330,6 @@ groups from right to left).
strings in a human recognizable way, compare using strings in a human recognizable way, compare using
:func:`unicodedata.normalize`. :func:`unicodedata.normalize`.
.. [#] The implementation computes this efficiently, without constructing lists
or sorting.
.. [#] Earlier versions of Python used lexicographic comparison of the sorted (key,
value) lists, but this was very expensive for the common case of comparing
for equality. An even earlier version of Python compared dictionaries by
identity only, but this caused surprises because people expected to be able
to test a dictionary for emptiness by comparing it to ``{}``.
.. [#] Due to automatic garbage-collection, free lists, and the dynamic nature of .. [#] Due to automatic garbage-collection, free lists, and the dynamic nature of
descriptors, you may notice seemingly unusual behaviour in certain uses of descriptors, you may notice seemingly unusual behaviour in certain uses of
the :keyword:`is` operator, like those involving comparisons between instance the :keyword:`is` operator, like those involving comparisons between instance