[Python-Dev] __module__ of newly-created extension classes

[David Abrahams]

When creating new-style classes from within an extension module, the
current behavior results in the __module__ attribute being set to the name
of the Python module which first imports the extension module.

I recall having a similar problem with my own extension classes in
Boost.Python v1, but was a little surprised to find that it persists in
Boost.Python v2, when creating new-style classes. A trivial inspection
reveals this bit of code in typeobject.c:

    /* Set __module__ in the dict */
    if (PyDict_GetItemString(dict, "__module__") == NULL) {
        tmp = PyEval_GetGlobals();
        if (tmp != NULL) {
            tmp = PyDict_GetItemString(tmp, "__name__");
            if (tmp != NULL) {
                if (PyDict_SetItemString(dict, "__module__",
                             tmp) < 0)
                    return NULL;
            }
        }
    }

I can work around this problem, but I wonder if it would be a good idea if
Python set __name__ automatically during the import of an extension module?
I realize that there are ways to undermine this, e.g. explicitly creating a
nested module object.

+---------------------------------------------------------------+
                  David Abrahams
      C++ Booster (http://www.boost.org)               O__  ==
      Pythonista (http://www.python.org)              c/ /'_ ==
  resume: http://users.rcn.com/abrahams/resume.html  (*) \(*) ==
          email: david.abrahams@rcn.com
+---------------------------------------------------------------+