Issue #4395: Better testing and documentation of binary operators.
Patch by Martin Panter.
diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst
index dda18ba..4acf13e 100644
--- a/Doc/reference/datamodel.rst
+++ b/Doc/reference/datamodel.rst
@@ -1266,10 +1266,14 @@
context (e.g., in the condition of an ``if`` statement), Python will call
:func:`bool` on the value to determine if the result is true or false.
- There are no implied relationships among the comparison operators. The truth
- of ``x==y`` does not imply that ``x!=y`` is false. Accordingly, when
- defining :meth:`__eq__`, one should also define :meth:`__ne__` so that the
- operators will behave as expected. See the paragraph on :meth:`__hash__` for
+ By default, :meth:`__ne__` delegates to :meth:`__eq__` and
+ inverts the result unless it is ``NotImplemented``. There are no other
+ implied relationships among the comparison operators, for example,
+ the truth of ``(x<y or x==y)`` does not imply ``x<=y``.
+ To automatically generate ordering operations from a single root operation,
+ see :func:`functools.total_ordering`.
+
+ See the paragraph on :meth:`__hash__` for
some important notes on creating :term:`hashable` objects which support
custom comparison operations and are usable as dictionary keys.
@@ -1278,11 +1282,11 @@
rather, :meth:`__lt__` and :meth:`__gt__` are each other's reflection,
:meth:`__le__` and :meth:`__ge__` are each other's reflection, and
:meth:`__eq__` and :meth:`__ne__` are their own reflection.
-
- Arguments to rich comparison methods are never coerced.
-
- To automatically generate ordering operations from a single root operation,
- see :func:`functools.total_ordering`.
+ If the operands are of different types, and right operand's type is
+ a direct or indirect subclass of the left operand's type,
+ the reflected method of the right operand has priority, otherwise
+ the left operand's method has priority. Virtual subclassing is
+ not considered.
.. method:: object.__hash__(self)