Memory Management in Embedded Python

[Huayang Xia]

Hi there,

I have a piece of code like this:

void funct(PyObject* pyobj)
{
char str[128];
strncpy(str, "just a test string", sizeof(str));
PyObject* pydata = PyObject_CallMethod(pyobj, "method_x",
"s", str);
Py_DECREF(pydata);
}

After the function is exited, the str is not there anymore. Will this
affect python operation. How does python use the str? It's copied or it
just uses the pointer?

Thanks in advance.

[=?ISO-8859-1?Q?=22Martin_v=2E_L=F6wis=22?=]

Huayang Xia schrieb:

I have a piece of code like this:

void funct(PyObject* pyobj)
{
char str[128];
strncpy(str, "just a test string", sizeof(str));
PyObject* pydata = PyObject_CallMethod(pyobj, "method_x",
"s", str);
Py_DECREF(pydata);
}

After the function is exited, the str is not there anymore. Will this
affect python operation. How does python use the str? It's copied or it
just uses the pointer?

The interpreter creates a string object, and passes that to method_x.
Creating a string object does indeed create a copy. The string object
will be refcounted, so it exists as long as there is a reference to it.
Likely (unless the method_x implementation somehow stores the string),
it gets deallocated before PyObject_Call returns.

HTH,
Martin