diff options
Diffstat (limited to 'Doc/library/constants.rst')
| -rw-r--r-- | Doc/library/constants.rst | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/Doc/library/constants.rst b/Doc/library/constants.rst index f17e1a3787..38dd552a03 100644 --- a/Doc/library/constants.rst +++ b/Doc/library/constants.rst @@ -19,19 +19,21 @@ A small number of constants live in the built-in namespace. They are: .. data:: None - The sole value of the type ``NoneType``. ``None`` is frequently used to - represent the absence of a value, as when default arguments are not passed to a - function. Assignments to ``None`` are illegal and raise a :exc:`SyntaxError`. + An object frequently used to represent the absence of a value, as when + default arguments are not passed to a function. Assignments to ``None`` + are illegal and raise a :exc:`SyntaxError`. + ``None`` is the sole instance of the :data:`NoneType` type. .. data:: NotImplemented - Special value which should be returned by the binary special methods + A 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. It should not be evaluated in a boolean context. + ``NotImplemented`` is the sole instance of the :data:`types.NotImplementedType` type. .. note:: @@ -59,8 +61,9 @@ A small number of constants live in the built-in namespace. They are: .. index:: single: ...; ellipsis literal .. data:: Ellipsis - The same as the ellipsis literal "``...``". Special value used mostly in conjunction + The same as the ellipsis literal "``...``". Special value used mostly in conjunction with extended slicing syntax for user-defined container data types. + ``Ellipsis`` is the sole instance of the :data:`types.EllipsisType` type. .. data:: __debug__ |