Merged revisions 58742-58816 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

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  r58745 | georg.brandl | 2007-11-01 10:19:33 -0700 (Thu, 01 Nov 2007) | 2 lines

  #1364: os.lstat is available on Windows too, as an alias to os.stat.
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  r58750 | christian.heimes | 2007-11-01 12:48:10 -0700 (Thu, 01 Nov 2007) | 1 line

  Backport of import tests for bug http://bugs.python.org/issue1293 and bug http://bugs.python.org/issue1342
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  r58751 | christian.heimes | 2007-11-01 13:11:06 -0700 (Thu, 01 Nov 2007) | 1 line

  Removed non ASCII text from test as requested by Guido. Sorry :/
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  r58753 | georg.brandl | 2007-11-01 13:37:02 -0700 (Thu, 01 Nov 2007) | 2 lines

  Fix markup glitch.
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  r58757 | gregory.p.smith | 2007-11-01 14:08:14 -0700 (Thu, 01 Nov 2007) | 4 lines

  Fix bug introduced in revision 58385.  Database keys could no longer
  have NULL bytes in them.  Replace the errant strdup with a
  malloc+memcpy.  Adds a unit test for the correct behavior.
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  r58758 | gregory.p.smith | 2007-11-01 14:15:36 -0700 (Thu, 01 Nov 2007) | 3 lines

  Undo revision 58533 58534 fixes.  Those were a workaround for
  a problem introduced by 58385.
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  r58759 | gregory.p.smith | 2007-11-01 14:17:47 -0700 (Thu, 01 Nov 2007) | 2 lines

  false "fix" undone as correct problem was found and fixed.
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  r58765 | mark.summerfield | 2007-11-02 01:24:59 -0700 (Fri, 02 Nov 2007) | 3 lines

  Added more file-handling related cross-references.
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  r58766 | nick.coghlan | 2007-11-02 03:09:12 -0700 (Fri, 02 Nov 2007) | 1 line

  Fix for bug 1705170 - contextmanager swallowing StopIteration (2.5 backport candidate)
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  r58784 | thomas.heller | 2007-11-02 12:10:24 -0700 (Fri, 02 Nov 2007) | 4 lines

  Issue #1292: On alpha, arm, ppc, and s390 linux systems the
  --with-system-ffi configure option defaults to "yes" because the
  bundled libffi sources are too old.
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  r58785 | thomas.heller | 2007-11-02 12:11:23 -0700 (Fri, 02 Nov 2007) | 1 line

  Enable the full ctypes c_longdouble tests again.
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  r58796 | georg.brandl | 2007-11-02 13:06:17 -0700 (Fri, 02 Nov 2007) | 4 lines

  Make "hashable" a glossary entry and clarify docs on __cmp__, __eq__ and __hash__.
  I hope the concept of hashability is better understandable now.
  Thanks to Tim Hatch for pointing out the flaws here.
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1 files changed, 14 insertions, 0 deletions

diff --git a/Doc/glossary.rst b/Doc/glossary.rst
index dfcbee8..aa69867 100644
--- a/Doc/glossary.rst
+++ b/Doc/glossary.rst
@@ -140,6 +140,20 @@ Glossary
       in the past to create a "free-threaded" interpreter (one which locks
       shared data at a much finer granularity), but performance suffered in the
       common single-processor case.
+
+   hashable
+      An object is *hashable* if it has a hash value that never changes during
+      its lifetime (it needs a :meth:`__hash__` method), and can be compared to
+      other objects (it needs an :meth:`__eq__` or :meth:`__cmp__` method).
+      Hashable objects that compare equal must have the same hash value.
+
+      Hashability makes an object usable as a dictionary key and a set member,
+      because these data structures use the hash value internally.
+
+      All of Python's immutable built-in objects are hashable, while all mutable
+      containers (such as lists or dictionaries) are not.  Objects that are
+      instances of user-defined classes are hashable by default; they all
+      compare unequal, and their hash value is their :func:`id`.
     
    IDLE
       An Integrated Development Environment for Python.  IDLE is a basic editor