Automatic ref-count management in C++ using a smart ptr，ref-countptr,Managing ref

Automatic ref-count management in C++ using a smart ptr，ref-countptr,Managing ref

Managing ref-counting is a complex and error prone business. If you choose C++to extend or embed Python, you can simply use a modification on std::auto_ptr.Instead of calling delete on the managed pointer, it will decref it.

So now you can do:

auto_py str = PyStr_FromString("Hello World!");

and forget about having to decref it altogether! Just like auto_ptr you canget the PyObject * with get(), release it from managed control with release(),and rebind it with reset(new_ptr). You can also incref it by calling inc(),but be cautious as you can easily create a leak by increfing once to much.

#include <memory>typedef std::auto_ptr<PyObject> auto_py_base;class auto_py : public auto_py_base {public:    auto_py(PyObject * obj = NULL) : auto_py_base(obj) {    }    ~auto_py() {        reset();    }    void reset(PyObject * obj = NULL) {        if(obj != get()) {            PyObject * old = release(); // Avoid the delete call            Py_XDECREF(old);            auto_py_base::reset(obj);        }    }    void inc() {        PyObject * ptr = get();        if(ptr)            Py_INCREF(ptr);    }};

You can do most of this with boost::python, but that library doesn't give youfull access to the Python C API, so when you need to pass around PyObjectpointers this comes in handy.