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| -rw-r--r-- | Doc/library/functools.rst | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/Doc/library/functools.rst b/Doc/library/functools.rst index a09d3cf725..8f9528a157 100644 --- a/Doc/library/functools.rst +++ b/Doc/library/functools.rst @@ -17,6 +17,26 @@ function for the purposes of this module. The :mod:`functools` module defines the following functions: +.. 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())) .. function:: reduce(function, iterable[, initializer]) |