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@@ -15,6 +15,51 @@ function for the purposes of this module.
The :mod:`functools` module defines the following functions:
+.. function:: cmp_to_key(func)
+
+ Transform an old-style comparison function to a key-function. Used with
+ tools that accept key functions (such as :func:`sorted`, :func:`min`,
+ :func:`max`, :func:`heapq.nlargest`, :func:`heapq.nsmallest`,
+ :func:`itertools.groupby`).
+ This function is primarily used as a transition tool for programs
+ being converted from Py2.x which supported the use of comparison
+ functions.
+
+ A compare function is any callable that accept two arguments, compares
+ them, and returns a negative number for less-than, zero for equality,
+ or a positive number for greater-than. A key function is a callable
+ that accepts one argument and returns another value that indicates
+ the position in the desired collation sequence.
+
+ Example::
+
+ sorted(iterable, key=cmp_to_key(locale.strcoll)) # locale-aware sort order
+
+ .. versionadded:: 3.2
+
+.. function:: total_ordering(cls)
+
+ Given a class defining one or more rich comparison ordering methods, this
+ class decorator supplies the rest. This simplies the effort involved
+ in specifying all of the possible rich comparison operations:
+
+ The class must define one of :meth:`__lt__`, :meth:`__le__`,
+ :meth:`__gt__`, or :meth:`__ge__`.
+ In addition, the class should supply an :meth:`__eq__` method.
+
+ For example::
+
+ @total_ordering
+ class Student:
+ def __eq__(self, other):
+ return ((self.lastname.lower(), self.firstname.lower()) ==
+ (other.lastname.lower(), other.firstname.lower()))
+ def __lt__(self, other):
+ return ((self.lastname.lower(), self.firstname.lower()) <
+ (other.lastname.lower(), other.firstname.lower()))
+
+ .. versionadded:: 3.2
+
.. function:: partial(func, *args, **keywords)
Return a new :class:`partial` object which when called will behave like *func*