A correct order of steps to perform what you are trying to do is: In the main thread: Initialize Python using Py_Initialize*. Initialize Python threading support using PyEval_InitThreads(). Start the C++ thread. At this point, the main thread still holds the GIL. In a C++ thread: Acquire the GIL using PyGILState_Ensure(). Create a new Python … Read more
Maybe you need to set extra_link_args, too? extra_compile_args is used when compiling the source code, extra_link_args when linking the result.
The error also occurs, when using boost::python, if the module name is different to the compiled .so file name. For example: hello.cpp #include <boost/python/module.hpp> #include <boost/python/def.hpp> using namespace std; using namespace boost::python; int helloWorld(){ cout << “Hello world!” << endl; return 0; } BOOST_PYTHON_MODULE(libhello) { def(“hello_world”, helloWorld); } compilation command: g++ -fpic -shared -o libfoo.so … Read more
Call PyObject_New(), followed by PyObject_Init(). EDIT: The best way is to call the class object, just like in Python itself: /* Pass two arguments, a string and an int. */ PyObject *argList = Py_BuildValue(“si”, “hello”, 42); /* Call the class object. */ PyObject *obj = PyObject_CallObject((PyObject *) &pyfoo_T, argList); /* Release the argument list. */ … Read more
Here is a C++ friendly solution I have developed lately. I explain a few details of it on my blog: Python sys.stdout redirection in C++ where I also point to repository at my GitHub where most recent version can be found. Here is complete example based on the current code at the time of posting … Read more
Your understanding is correct: invoking PyEval_InitThreads does, among other things, acquire the GIL. In a correctly written Python/C application, this is not an issue because the GIL will be unlocked in time, either automatically or manually. If the main thread goes on to run Python code, there is nothing special to do, because Python interpreter … Read more
The difference mainly arises with mutable vs immutable types. __new__ accepts a type as the first argument, and (usually) returns a new instance of that type. Thus it is suitable for use with both mutable and immutable types. __init__ accepts an instance as the first argument and modifies the attributes of that instance. This is … Read more
As explained before, using PyRun_SimpleString seems to be a bad idea. You should definitely use the methods provided by the C-API (http://docs.python.org/c-api/). Reading the introduction is the first thing to do to understand the way it works. First, you have to learn about PyObject that is the basic object for the C API. It can … Read more
fatal error: Python.h: No such file or directory