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Document that __cmp__() is not defined for sets. 

Note, that list.sort() is undefined for lists of sets.
Add the ... prompt to the example so it runs in doctest.
This commit is contained in:
Raymond Hettinger 2003-01-15 15:46:05 +00:00
parent b32c886d71
commit 3801ec7ff3
1 changed files with 12 additions and 3 deletions
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15
Doc/lib/libsets.tex
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@ -110,6 +110,15 @@ subset of the second set (is a subset, but is not equal).
A set is greater than another set if and only if the first set is a proper A set is greater than another set if and only if the first set is a proper
superset of the second set (is a superset, but is not equal). superset of the second set (is a superset, but is not equal).
The subset and equality comparisons do not generalize to a complete
ordering function. For example, any two disjoint sets are not equal and
are not subsets of each other, so \emph{none} of the following are true:
\code{\var{a}<\var{b}}, \code{\var{a}==\var{b}}, or \code{\var{a}>\var{b}}.
Accordingly, sets do not implement the \method{__cmp__} method.
Since sets only define partial ordering (subset relationships), the output
of the \method{list.sort()} method is undefined for lists of sets.
The following table lists operations available in \class{ImmutableSet} The following table lists operations available in \class{ImmutableSet}
but not found in \class{Set}: but not found in \class{Set}:
@ -175,9 +184,9 @@ False
>>> employees.issuperset(engineers) >>> employees.issuperset(engineers)
True True
>>> for group in [engineers, programmers, management, employees]: >>> for group in [engineers, programmers, management, employees]:
group.discard('Susan') # unconditionally remove element ... group.discard('Susan') # unconditionally remove element
print group ... print group
...
Set(['Jane', 'Marvin', 'Janice', 'John', 'Jack']) Set(['Jane', 'Marvin', 'Janice', 'John', 'Jack'])
Set(['Janice', 'Jack', 'Sam']) Set(['Janice', 'Jack', 'Sam'])
Set(['Jane', 'Zack', 'Jack']) Set(['Jane', 'Zack', 'Jack'])