diff options
Diffstat (limited to 'Doc')
| -rw-r--r-- | Doc/reference/datamodel.rst | 22 |
1 files changed, 13 insertions, 9 deletions
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 @@ Basic customization 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 @@ Basic customization 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) |