Am Dienstag, 29. Juli 2008 12:51:36 schrieb code_berzerker: > Ok now more seriously. I have question refering to char* used as > function parameters to return values. I have read SWIG manual to find > best way to overcome that, but there are many warnings about memory > leaks and stuff, so I feel confused. > > Ok to put it more simply: how to safely define a variable in Python > and have it modified by C/C++ function?
At least for strings, this won't work. Python strings are immutable (and Python optimizes some things based on this knowledge), and as such you can pass a Python string(-object) into a C/C++ function and retrieve its value there as a const (!) char* using the PyString_*-API (I have no idea how this is encapsulated in SWIG), but cannot/should not modify it (a const_cast<> is almost always a sign of bad programming, anyway). The only real choice you have is to have your wrapper return a new string object, created using one of the PyString_FromString[AndSize] functions. Check the Python C-API documentation for more info on this. Anyway, on a different note, I personally have always found it simpler to not use SWIG to generate C extensions for Python, but to use the Python C-API directly. Hope this helps! -- Heiko Wundram -- http://mail.python.org/mailman/listinfo/python-list
