python - 在对象上调用方法

Question

给定一个指向 python 对象的 PyObject*，我如何调用其中一个对象方法？文档从未给出这样的例子:

PyObject* obj = ....
PyObject* args = Py_BuildValue("(s)", "An arg");
PyObject* method = PyWHATGOESHERE(obj, "foo");
PyObject* ret = PyWHATGOESHERE(obj, method, args);
if (!ret) {
   // check error...
}

这相当于

>>> ret = obj.foo("An arg")

Answer 1

PyObject* obj = ....
PyObject *ret = PyObject_CallMethod(obj, "foo", "(s)", "An arg");
if (!ret) {
   // check error...
}

阅读 Python C API documentation .在这种情况下，您需要 object protocol .

PyObject* PyObject_CallMethod(PyObject *o, char *method, char *format, ...)

Return value: New reference.

Call the method named method of object o with a variable number of C arguments. The C arguments are described by a Py_BuildValue() format string that should produce a tuple. The format may be NULL, indicating that no arguments are provided. Returns the result of the call on success, or NULL on failure. This is the equivalent of the Python expression o.method(args). Note that if you only pass PyObject * args, PyObject_CallMethodObjArgs() is a faster alternative.

和

PyObject* PyObject_CallMethodObjArgs(PyObject *o, PyObject *name, ..., NULL)

Return value: New reference.

Calls a method of the object o, where the name of the method is given as a Python string object in name. It is called with a variable number of PyObject* arguments. The arguments are provided as a variable number of parameters followed by NULL. Returns the result of the call on success, or NULL on failure.