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authorSenthil Kumaran <orsenthil@gmail.com>2010-07-14 20:30:02 (GMT)
committerSenthil Kumaran <orsenthil@gmail.com>2010-07-14 20:30:02 (GMT)
commit0736767fdfef56f6ebc1306052590f0f704187d6 (patch)
treebad5765e9b200ea1bd73e2e9cb21a5d6b714a30c /Doc/reference
parent04f31b8ae6cc2a1aea70ea184d16b3a3dc2048dd (diff)
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Fix issue9132 - Documentation for comparing dictionaries is out of date
Diffstat (limited to 'Doc/reference')
-rw-r--r--Doc/reference/expressions.rst15
1 files changed, 3 insertions, 12 deletions
diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst
index e568ddf..b61ec08 100644
--- a/Doc/reference/expressions.rst
+++ b/Doc/reference/expressions.rst
@@ -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
sequence is ordered first (for example, ``[1,2] < [1,2,3]``).
-* Mappings (dictionaries) compare equal if and only if their sorted ``(key,
- value)`` lists compare equal. [#]_ Outcomes other than equality are resolved
- consistently, but are not otherwise defined. [#]_
+* Mappings (dictionaries) compare equal if and only if they have the same
+ ``(key, value)`` pairs. Order comparisons ``('<', '<=', '>=', '>')``
+ raise :exc:`TypeError`.
* Sets and frozensets define comparison operators to mean subset and superset
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
: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
descriptors, you may notice seemingly unusual behaviour in certain uses of
the :keyword:`is` operator, like those involving comparisons between instance