python class in c / global calls

Thomas Grill t.grill at gmx.net
Fri Aug 23 19:33:04 CEST 2002


Ok, here's the self reply....
Of course it was some Py_DECREF from a borrowed reference......

thanks for your attention
Thomas



"Thomas Grill" <t.grill at gmx.net> schrieb im Newsbeitrag
news:3d66663a$0$14706$3b214f66 at news.univie.ac.at...
> Hi list,
> i hope you can help me with this one.
> I am working on a Python scripting extension to a library for algorithmic
> composition (music, that is),
> therefore a have to embed the Python interpreter and steer it from within
c.
>
> I managed to implement a python class in c by following the recipe
> http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/54352,
> which makes a new module and a dictionary and defines the methods one
wants
> to have. See below for more details.
>
> Here's some python code that I execute from c:
>
> ############
> import pyext
> import time
>
> print time.time()
>
> # derive class from pyext.pybase
> class testcl1(pyext.pybase):
>     def fun(self):
>         print "Hello"
>         print time.time()
>
> ###############
>
> Loading of the code yields no error and prints some number to the console
> which corresponds to the time.
> So far, so good.
> Now, i construct the class "testcl1" in c and call its method "fun".
> It prints "Hello" to the console, but then, the module time isn't
recognized
> any more!
> It says:
>
> >Traceback (most recent call last):
> >File "scripts\ext1.py", line 9, in fun
> >   print time.time()
> >AttributeError: 'NoneType' object has no attribute 'time'
>
>
> Why that? Is that some basic Python knowledge that i'm lacking?
> Or is the class construction in c incomplete?
> Please see the details of the c code below for reference.
>
> many thanks for any pointers!!
> Thomas
>
> PS. Please CC: me, i am not always following the list
>
> -----------------------------
> This is the class construction code:
>
>
> static PyMethodDef pyext_meths[] =
> {
>     {"__init__", pyext::py__init__, METH_VARARGS, "pyext init"},
>     {NULL, NULL, 0, NULL}        /* Sentinel */
> };
>
> static PyMethodDef pyext_mod_meths[] = {{NULL, NULL, 0, NULL}};
>
>
>   PyObject *module = Py_InitModule("pyext", pyext_mod_meths);
>
>   PyObject *moduleDict = PyModule_GetDict(module);
>   PyObject *classDict = PyDict_New();
>   PyObject *className = PyString_FromString("pybase");
>
>   PyObject *fooClass = PyClass_New(NULL, classDict, className);
>   PyDict_SetItemString(moduleDict, "pybase", fooClass);
>   Py_DECREF(classDict);
>   Py_DECREF(className);
>   Py_DECREF(fooClass);
>
>   // add methods to class
>   for (PyMethodDef *def = pyext_meths; def->ml_name != NULL; def++) {
>    PyObject *func = PyCFunction_New(def, NULL);
>    PyObject *method = PyMethod_New(func, NULL, fooClass);
>    PyDict_SetItemString(classDict, def->ml_name, method);
>    Py_DECREF(func);
>    Py_DECREF(method);
>   }
>
>
>
>
>





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