Re: [Libguestfs] [nbdkit PATCH 2/2] python: Simplify calling into plugin

PyObject_CallObject is powerful, but awkward - we have to wrap all arguments into a temporary tuple before using it. Let python do more of the work by using PyObject_CallFunction anywhere that all arguments can be described by a Py_BuildValue() format string, instead of creating one-shot arguments ourselves. In fact, for our py_config(), this makes it easier to not worry about python 2 String vs. python 3 Unicode. Similarly, PyObject_CallFunctionObjArgs is nicer when we already have PyObjects for all parameters (including in py_open(), where we can't use a Py_BuildValue() string for converting a C int into Py_True or Py_False, but can easily avoid the tuple wrapper).

@@ -436,20 +406,15 @@ py_pwrite (void *handle, const void *buf, { PyObject *obj = handle; PyObject *fn; - PyObject *args; PyObject *r; if (callback_defined ("pwrite", &fn)) { PyErr_Clear (); - args = PyTuple_New (3); - Py_INCREF (obj); /* decremented by Py_DECREF (args) */ - PyTuple_SetItem (args, 0, obj); - PyTuple_SetItem (args, 1, PyByteArray_FromStringAndSize (buf, count)); - PyTuple_SetItem (args, 2, PyLong_FromUnsignedLongLong (offset)); - r = PyObject_CallObject (fn, args); + r = PyObject_CallFunction (fn, "OOL", obj, + PyByteArray_FromStringAndSize (buf, count), + offset, NULL);