Add PyContextVar_NewThreadInheritable().

Author: nascheme

Doc/c-api/contextvars.rst

@@ -157,6 +157,14 @@ Context variable functions:
    a default value for the context variable, or ``NULL`` for no default.
    If an error has occurred, this function returns ``NULL``.
 
+.. c:function:: PyObject *PyContextVar_NewThreadInheritable(const char *name, PyObject *def)
+
+   Create a new ``ContextVar`` object whose bindings are inherited by new
+   :class:`threading.Thread` instances.  The parameters and return value are
+   the same as for :c:func:`PyContextVar_New`.
+
+   .. versionadded:: 3.16
+
 .. c:function:: int PyContextVar_Get(PyObject *var, PyObject *default_value, PyObject **value)
 
    Get the value of a context variable.  Returns ``-1`` if an error has

Include/cpython/context.h

@@ -68,6 +68,13 @@ PyAPI_FUNC(int) PyContext_ClearWatcher(int watcher_id);
 PyAPI_FUNC(PyObject *) PyContextVar_New(
     const char *name, PyObject *default_value);
 
+/* Create a new thread-inheritable context variable.
+
+   default_value can be NULL.
+*/
+PyAPI_FUNC(PyObject *) PyContextVar_NewThreadInheritable(
+    const char *name, PyObject *default_value);
+
 
 /* Get a value for the variable.
 

Python/context.c

@@ -281,18 +281,31 @@ PyContext_Exit(PyObject *octx)
 }
 
 
-PyObject *
-PyContextVar_New(const char *name, PyObject *def)
+static PyObject *
+contextvar_new_from_utf8(const char *name, PyObject *def,
+                         int thread_inheritable)
 {
     PyObject *pyname = PyUnicode_FromString(name);
     if (pyname == NULL) {
         return NULL;
     }
-    PyContextVar *var = contextvar_new(pyname, def, 0);
+    PyContextVar *var = contextvar_new(pyname, def, thread_inheritable);
     Py_DECREF(pyname);
     return (PyObject *)var;
 }
 
+PyObject *
+PyContextVar_New(const char *name, PyObject *def)
+{
+    return contextvar_new_from_utf8(name, def, 0);
+}
+
+PyObject *
+PyContextVar_NewThreadInheritable(const char *name, PyObject *def)
+{
+    return contextvar_new_from_utf8(name, def, 1);
+}
+
 
 int
 PyContextVar_Get(PyObject *ovar, PyObject *def, PyObject **val)