diff options
Diffstat (limited to 'Doc/library/typing.rst')
| -rw-r--r-- | Doc/library/typing.rst | 82 |
1 files changed, 79 insertions, 3 deletions
diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst index 573318b..e062872 100644 --- a/Doc/library/typing.rst +++ b/Doc/library/typing.rst @@ -1614,7 +1614,7 @@ without the dedicated syntax, as documented below. .. _typevar: -.. class:: TypeVar(name, *constraints, bound=None, covariant=False, contravariant=False, infer_variance=False) +.. class:: TypeVar(name, *constraints, bound=None, covariant=False, contravariant=False, infer_variance=False, default=typing.NoDefault) Type variable. @@ -1752,15 +1752,35 @@ without the dedicated syntax, as documented below. the constraints are evaluated only when the attribute is accessed, not when the type variable is created (see :ref:`lazy-evaluation`). + .. attribute:: __default__ + + The default value of the type variable, or :data:`typing.NoDefault` if it + has no default. + + .. versionadded:: 3.13 + + .. method:: has_default() + + Return whether or not the type variable has a default value. This is equivalent + to checking whether :attr:`__default__` is not the :data:`typing.NoDefault` + singleton, except that it does not force evaluation of the + :ref:`lazily evaluated <lazy-evaluation>` default value. + + .. versionadded:: 3.13 + .. versionchanged:: 3.12 Type variables can now be declared using the :ref:`type parameter <type-params>` syntax introduced by :pep:`695`. The ``infer_variance`` parameter was added. + .. versionchanged:: 3.13 + + Support for default values was added. + .. _typevartuple: -.. class:: TypeVarTuple(name) +.. class:: TypeVarTuple(name, default=typing.NoDefault) Type variable tuple. A specialized form of :ref:`type variable <typevar>` that enables *variadic* generics. @@ -1870,6 +1890,22 @@ without the dedicated syntax, as documented below. The name of the type variable tuple. + .. attribute:: __default__ + + The default value of the type variable tuple, or :data:`typing.NoDefault` if it + has no default. + + .. versionadded:: 3.13 + + .. method:: has_default() + + Return whether or not the type variable tuple has a default value. This is equivalent + to checking whether :attr:`__default__` is not the :data:`typing.NoDefault` + singleton, except that it does not force evaluation of the + :ref:`lazily evaluated <lazy-evaluation>` default value. + + .. versionadded:: 3.13 + .. versionadded:: 3.11 .. versionchanged:: 3.12 @@ -1877,7 +1913,11 @@ without the dedicated syntax, as documented below. Type variable tuples can now be declared using the :ref:`type parameter <type-params>` syntax introduced by :pep:`695`. -.. class:: ParamSpec(name, *, bound=None, covariant=False, contravariant=False) + .. versionchanged:: 3.13 + + Support for default values was added. + +.. class:: ParamSpec(name, *, bound=None, covariant=False, contravariant=False, default=typing.NoDefault) Parameter specification variable. A specialized version of :ref:`type variables <typevar>`. @@ -1946,6 +1986,22 @@ without the dedicated syntax, as documented below. The name of the parameter specification. + .. attribute:: __default__ + + The default value of the parameter specification, or :data:`typing.NoDefault` if it + has no default. + + .. versionadded:: 3.13 + + .. method:: has_default() + + Return whether or not the parameter specification has a default value. This is equivalent + to checking whether :attr:`__default__` is not the :data:`typing.NoDefault` + singleton, except that it does not force evaluation of the + :ref:`lazily evaluated <lazy-evaluation>` default value. + + .. versionadded:: 3.13 + Parameter specification variables created with ``covariant=True`` or ``contravariant=True`` can be used to declare covariant or contravariant generic types. The ``bound`` argument is also accepted, similar to @@ -1959,6 +2015,10 @@ without the dedicated syntax, as documented below. Parameter specifications can now be declared using the :ref:`type parameter <type-params>` syntax introduced by :pep:`695`. + .. versionchanged:: 3.13 + + Support for default values was added. + .. note:: Only parameter specification variables defined in global scope can be pickled. @@ -3171,6 +3231,22 @@ Introspection helpers .. versionadded:: 3.7.4 +.. data:: NoDefault + + A sentinel object used to indicate that a type parameter has no default + value. For example: + + .. doctest:: + + >>> T = TypeVar("T") + >>> T.__default__ is typing.NoDefault + True + >>> S = TypeVar("S", default=None) + >>> S.__default__ is None + True + + .. versionadded:: 3.13 + Constant -------- |