Abstract over CPython tuple API

cassandra/tuple.pxd

@@ -0,0 +1,27 @@
+from cpython.tuple cimport (
+        PyTuple_New,
+        # Return value: New reference.
+        # Return a new tuple object of size len, or NULL on failure.
+        PyTuple_SET_ITEM,
+        # Like PyTuple_SetItem(), but does no error checking, and should
+        # only be used to fill in brand new tuples. Note: This function
+        # ``steals'' a reference to o.
+        )
+
+from cpython.ref cimport (
+        Py_INCREF
+        # void Py_INCREF(object o)
+        #     Increment the reference count for object o. The object must not
+        #     be NULL; if you aren't sure that it isn't NULL, use
+        #     Py_XINCREF().
+        )
+
+cdef inline tuple tuple_new(Py_ssize_t n):
+    """Allocate a new tuple object"""
+    return PyTuple_New(n)
+
+cdef inline void tuple_set(tuple tup, Py_ssize_t idx, object item):
+    """Insert new object into tuple. No item must have been set yet."""
+    # PyTuple_SET_ITEM steals a reference, so we need to INCREF
+    Py_INCREF(item)
+    PyTuple_SET_ITEM(tup, idx, item)