[EMAIL PROTECTED] wrote: > Hi. > > I trying to write an extension module to call some C libraries so I can > use them in Python. Several of the library functions pass pointers to > structures as arguments. I was thinking that I could create a class for > each structure, but I'm not sure how to get the data back and forth. > The example the "Extending and Embedding the Python Interpreter" manual > has examples of passing strings and ints using > PyArg_ParseTupleAndKeywords(), but it's not clear to me if I can even > pass structs around like this. > > I'm just learning how to do extensions, so any help is greatly > appreciated.
There are several ways you can accomplish this. You could use the module "struct" to create byte-string representations of your structs and pass these to your extension. In C, you just cast the string-pointer to your struct and pass it. Disadvantages are: low security, and cumbersome on the python side. Another way would be to pass the structures as python structures - tuples and/or lists. Then manually disassemble these is the extension (PyArg_ParseTupleAndKeywords and co. help you a great deal here) and create an instance of the desired struct. A third way could be to create an extension type that resembles your struct and use that to create the "real" struct by getting the types instance values. HTH -- Regards, Diez B. Roggisch -- http://mail.python.org/mailman/listinfo/python-list
