python-c-api

Numpy arrays, being extension types (aka defined using in extensions the C API), declare additional fields outside the scope of the Python interpreter (for example the data attribute, which is a Buffer Structure , as documented in Numpy's array interface . To be able to serialize it, Python 2 used to use the __reduce__ function as part of the pickle protocol, as stated in the doc , and explained here . But, even if __reduce__ still exists in Python 3, the Pickle protocol section (and Pickling and unpickling extension types a fortiori) was removed from the doc, so it is unclear what does what.

This question already has answers here : PyEval_InitThreads in Python 3: How/when to call it? (the saga continues ad nauseam) (7 answers) Closed 6 years ago . I'm a bit confused about when I'm supposed to call PyEval_InitThreads . In general, I understand that PyEval_InitThreads must be called whenever a non-Python thread (i.e. a thread that is spawned within an extension module) is used. However, I'm confused if PyEval_InitThreads is for C programs which embed the Python interpreter, or Python programs which import C-extension modules, or both. So, if I write a C extension module that will

I have Python extension module written in C. I want to use in this C code one of the standard Python modules, for example os or shutil . How is best to do this? PyObject* os = PyImport_ImportModuleNoBlock("os"); if (os == NULL) return NULL; someattr = PyObject_GetAttrString(os, "someattr"); Py_DECREF(os); If you import the module only once e.g., in init_yourmodule() function then use PyImport_ImportModule("os") . Don't. Instead, change your extension module so that it provides a service to Python, and then write Python code which calls os , shutil and your module. In fact, for a lot of the

I want to work with my Numpy arrays in a C extension. Many examples in this case uses the structure of PyArrayObject, array->data , array->strides[0] , array->strides[1] , ... pointers in order to reach the data, if I wanted to reach my array in a more familiar (or tidier) way to me, with indices like array[i][j] how should I proceed so? Should I typecast (bool *) array->data and work with the C array I created? (my elements are bools) My function declaration for now is (not finished, of course) static PyObject * xor_masking(PyObject *self, PyObject *args) { PyObject *input; PyObject *mask;

If I do (e.g.) open("/snafu/fnord") in Python (and the file does not exist), I get a traceback and the message IOError: [Errno 2] No such file or directory: '/snafu/fnord' I would like to get the above string with Python's C API (i.e., a Python interpreter embedded in a C program). I need it as a string, not output to the console. With PyErr_Fetch() I can get the type object of the exception and the value. For the above example, the value is a tuple: (2, 'No such file or directory', '/snafu/fnord') Is there an easy way from the information I get from PyErr_Fetch() to the string the Python

I am embedding Python in a C++ library which I am making. I would like users to be able to pass C functions in the form of function pointers PyObject* (fpFunc*)(PyObject*,PyObject*); so that I can use those functions in the embedded Python. So I have a function pointer and I know that it is possible to put this function as a module's method using a PyMethodDef struct and passing it to Py_InitModule("module", ModMethods); and thus obtaining a PyObject* module which I can easily grab functions from. But, what I would really appreciate is to be able to create this function on the fly without