How do I embed a python library in a C++ app?

Question

I've embedded python on a mobile device successfully, but now how do I include a python library such as urllib?

Additionally, how can I include my own python scripts without a PYTHONPATH?

(please note: python is not installed on this system)

Answer 1

The easiest way is to create a .zip file containing all the python code you need and add this to your process's PYTHONPATH environment variable (via setenv()) prior to initializing the embedded Python interpreter. Usage of .pyd libraries can be done similarly by adding them to the same directory as the .zip and including the directory in the PYTHONPATH as well.

Usage of the setenv() call can cause trouble on Windows if you're mixing c-runtime versions. I spent many aggrivating hours learing that setenv() only sets the environment variables for the version of the c-runtime your compiler ships with. So if, for example, Python was built with VC++ 2005 and your compiler is VC++ 2008, you'll need to use an alternative mechanism. Browsing the sources for py2exe and/or PyInstaller may provide you with a better solution (since you're doing essentially the same thing as these tools) but a simple alternative is to "cheat" by using PyRun_SimpleString() to set the module search path from within Python itself.

snprintf(buff, "import sys\nsys.path.append("%s")\n", py_zip_filename)
PyRun_SimpleString(buff)