https://hg.python.org/cpython/rev/b6ee02acaae9 changeset: 93615:b6ee02acaae9 parent: 93612:d502b5d60e00 parent: 93614:ebb8865dcf54 user: Ethan Furman <ethan@stoneleaf.us> date: Wed Nov 26 21:17:53 2014 -0800 summary: Issue22780: reword NotImplemented docs to emphasise should files: Doc/library/constants.rst | 20 +++++++++++++++++--- Doc/library/numbers.rst | 2 ++ Doc/reference/datamodel.rst | 7 ++++++- 3 files changed, 25 insertions(+), 4 deletions(-) diff --git a/Doc/library/constants.rst b/Doc/library/constants.rst --- a/Doc/library/constants.rst +++ b/Doc/library/constants.rst @@ -26,9 +26,23 @@ .. data:: NotImplemented - Special value which should be returned by the special methods - (:meth:`__eq__`, :meth:`__lt__`, :meth:`__add__`, etc.) to indicate - that the operation is not implemented with respect to the other type. + Special value which should be returned by the binary special methods + (e.g. :meth:`__eq__`, :meth:`__lt__`, :meth:`__add__`, :meth:`__rsub__`, + etc.) to indicate that the operation is not implemented with respect to + the other type; may be returned by the in-place binary special methods + (e.g. :meth:`__imul__`, :meth:`__iand__`, etc.) for the same purpose. + Its truth value is true. + +.. note:: + + When ``NotImplemented`` is returned, the interpreter will then try the + reflected operation on the other type, or some other fallback, depending + on the operator. If all attempted operations return ``NotImplemented``, the + interpreter will raise an appropriate exception. + + See + :ref:`implementing-the-arithmetic-operations` + for more details. .. data:: Ellipsis diff --git a/Doc/library/numbers.rst b/Doc/library/numbers.rst --- a/Doc/library/numbers.rst +++ b/Doc/library/numbers.rst @@ -110,6 +110,8 @@ MyFoo.register(Real) +.. _implementing-the-arithmetic-operations: + Implementing the arithmetic operations ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst --- a/Doc/reference/datamodel.rst +++ b/Doc/reference/datamodel.rst @@ -154,11 +154,16 @@ This type has a single value. There is a single object with this value. This object is accessed through the built-in name ``NotImplemented``. Numeric methods - and rich comparison methods may return this value if they do not implement the + and rich comparison methods should return this value if they do not implement the operation for the operands provided. (The interpreter will then try the reflected operation, or some other fallback, depending on the operator.) Its truth value is true. + See + :ref:`implementing-the-arithmetic-operations` + for more details. + + Ellipsis .. index:: object: Ellipsis -- Repository URL: https://hg.python.org/cpython