Make PySet_Add() work with frozensets.
Works like PyTuple_SetItem() to build-up values in a brand new frozenset.
Also, PyFrozenSet_New() is now guaranteed to produce a distinct new frozenset.
diff --git a/Doc/c-api/set.rst b/Doc/c-api/set.rst
index e677c05..2ed93e9 100644
--- a/Doc/c-api/set.rst
+++ b/Doc/c-api/set.rst
@@ -86,6 +86,11 @@
set on success or *NULL* on failure. Raise :exc:`TypeError` if *iterable* is
not actually iterable.
+ .. versionchanged:: 2.6
+ Now guaranteed to return a brand-new :class:`frozenset`. Formerly,
+ frozensets of zero-length were a singleton. This got in the way of
+ building-up new frozensets with :meth:`PySet_Add`.
+
The following functions and macros are available for instances of :class:`set`
or :class:`frozenset` or instances of their subtypes.
@@ -112,9 +117,6 @@
the *key* is unhashable. Raise :exc:`PyExc_SystemError` if *anyset* is not a
:class:`set`, :class:`frozenset`, or an instance of a subtype.
-The following functions are available for instances of :class:`set` or its
-subtypes but not for instances of :class:`frozenset` or its subtypes.
-
.. cfunction:: int PySet_Add(PyObject *set, PyObject *key)
@@ -124,6 +126,14 @@
Raise a :exc:`SystemError` if *set* is an not an instance of :class:`set` or its
subtype.
+ .. versionchanged:: 2.6
+ Now works with instances of :class:`frozenset` or its subtypes.
+ Like :cfunc:`PyTuple_SetItem` in that it can be used to fill-in the
+ values of brand new frozensets before they are exposed to other code.
+
+The following functions are available for instances of :class:`set` or its
+subtypes but not for instances of :class:`frozenset` or its subtypes.
+
.. cfunction:: int PySet_Discard(PyObject *set, PyObject *key)