Issue 2235: document PyObject_HashNotImplemented
This commit is contained in:
parent
f70385a5c3
commit
6e8fef07e5
|
@ -269,6 +269,16 @@ is considered sufficient for this determination.
|
|||
This is the equivalent of the Python expression ``hash(o)``.
|
||||
|
||||
|
||||
.. cfunction:: long PyObject_HashNotImplemented(PyObject *o)
|
||||
|
||||
Set a TypeError indicating that ``type(o)`` is not hashable and return ``-1``.
|
||||
This function receives special treatment when stored in a ``tp_hash`` slot,
|
||||
allowing a type to explicit indicate to the interpreter that it is not
|
||||
hashable.
|
||||
|
||||
.. versionadded:: 2.6
|
||||
|
||||
|
||||
.. cfunction:: int PyObject_IsTrue(PyObject *o)
|
||||
|
||||
Returns ``1`` if the object *o* is considered to be true, and ``0`` otherwise.
|
||||
|
|
|
@ -324,6 +324,14 @@ type objects) *must* have the :attr:`ob_size` field.
|
|||
error occurs during the computation of the hash value, the function should set
|
||||
an exception and return ``-1``.
|
||||
|
||||
This field can be set explicitly to :cfunc:`PyObject_HashNotImplemented` to
|
||||
block inheritance of the hash method from a parent type. This is interpreted
|
||||
as the equivalent of ``__hash__ = None`` at the Python level, causing
|
||||
``isinstance(o, collections.Hashable)`` to correctly return ``False``. Note
|
||||
that the converse is also true - setting ``__hash__ = None`` on a class at
|
||||
the Python level will result in the ``tp_hash`` slot being set to
|
||||
:cfunc:`PyObject_HashNotImplemented`.
|
||||
|
||||
When this field is not set, two possibilities exist: if the :attr:`tp_compare`
|
||||
and :attr:`tp_richcompare` fields are both *NULL*, a default hash value based on
|
||||
the object's address is returned; otherwise, a :exc:`TypeError` is raised.
|
||||
|
|
|
@ -166,6 +166,9 @@ Build
|
|||
Documentation
|
||||
-------------
|
||||
|
||||
- Issue #2235: the C API function PyObject_HashNotImplemented and its
|
||||
interaction with the tp_hash slot (added in 2.6b2) are now documented
|
||||
|
||||
- Issue #643841: The language reference now provides more detailed
|
||||
coverage of the lookup process for special methods. The disclaimers
|
||||
regarding lack of coverage of new-style classes have also been
|
||||
|
|
Loading…
Reference in New Issue