Merged revisions 67243,67245,67277-67278,67289 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
........
r67243 | benjamin.peterson | 2008-11-17 15:39:05 -0600 (Mon, 17 Nov 2008) | 1 line
a few fixes on the download page
........
r67245 | benjamin.peterson | 2008-11-17 16:05:19 -0600 (Mon, 17 Nov 2008) | 1 line
improve __hash__ docs
........
r67277 | skip.montanaro | 2008-11-18 21:35:41 -0600 (Tue, 18 Nov 2008) | 1 line
patch from issue 1108
........
r67278 | georg.brandl | 2008-11-19 01:59:09 -0600 (Wed, 19 Nov 2008) | 2 lines
Try to fix problems with verbatim.
........
r67289 | brett.cannon | 2008-11-19 14:29:39 -0600 (Wed, 19 Nov 2008) | 2 lines
Ignore .pyc and .pyo files.
........
diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst
index a531350..94bcb1b 100644
--- a/Doc/reference/datamodel.rst
+++ b/Doc/reference/datamodel.rst
@@ -1202,20 +1202,22 @@
object: dictionary
builtin: hash
- Called for the key object for dictionary operations, and by the built-in
- function :func:`hash`. Should return an integer usable as a hash value
- for dictionary operations. The only required property is that objects which
- compare equal have the same hash value; it is advised to somehow mix together
- (e.g., using exclusive or) the hash values for the components of the object that
- also play a part in comparison of objects.
+ Called by built-in function :func:`hash` and for operations on members of
+ hashed collections including :class:`set`, :class:`frozenset`, and
+ :class:`dict`. :meth:`__hash__` should return an integer. The only required
+ property is that objects which compare equal have the same hash value; it is
+ advised to somehow mix together (e.g. using exclusive or) the hash values for
+ the components of the object that also play a part in comparison of objects.
If a class does not define an :meth:`__eq__` method it should not define a
:meth:`__hash__` operation either; if it defines :meth:`__eq__` but not
- :meth:`__hash__`, its instances will not be usable as dictionary keys. If a
- class defines mutable objects and implements an :meth:`__eq__` method, it
- should not implement :meth:`__hash__`, since the dictionary implementation
- requires that a key's hash value is immutable (if the object's hash value
- changes, it will be in the wrong hash bucket).
+ :meth:`__hash__`, its instances will not be usable as items in hashable
+ collections. If a class defines mutable objects and implements an
+ :meth:`__eq__` method, it should not implement :meth:`__hash__`, since the
+ implementation of hashable collections requires that a key's hash value is
+ immutable (if the object's hash value changes, it will be in the wrong hash
+ bucket).
+
User-defined classes have :meth:`__eq__` and :meth:`__hash__` methods
by default; with them, all objects compare unequal (except with themselves)