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(3.4) Issue22780: reword NotImplemented docs to emphasise should

This commit is contained in:
Ethan Furman 2014-11-26 21:15:35 -08:00
parent e823933f9f
commit b004943e9b
3 changed files with 26 additions and 4 deletions
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21
Doc/library/constants.rst
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@ -26,9 +26,24 @@ A small number of constants live in the built-in namespace. They are:
.. data:: NotImplemented
Special value which can be returned by the "rich comparison" special methods
(:meth:`__eq__`, :meth:`__lt__`, and friends), to indicate that the comparison
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

2
Doc/library/numbers.rst
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@ -110,6 +110,8 @@ those. You can add ``MyFoo`` between :class:`Complex` and
MyFoo.register(Real)
.. _implementing-the-arithmetic-operations:
Implementing the arithmetic operations
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

7
Doc/reference/datamodel.rst
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@ -154,11 +154,16 @@ NotImplemented
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