File I/O in the Python 3 C API
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23-08-2019 - |
Question
The C API in Python 3.0 has changed (deprecated) many of the functions for File Objects.
Before, in 2.X, you could use
PyObject* PyFile_FromString(char *filename, char *mode)
to create a Python file object, e.g:
PyObject *myFile = PyFile_FromString("test.txt", "r");
...but such function no longer exists in Python 3.0. What would be the Python 3.0 equivalent to such call?
Solution
You can do it the old(new?)-fashioned way, by just calling the io module.
This code works, but it does no error checking. See the docs for explanation.
PyObject *ioMod, *openedFile;
PyGILState_STATE gilState = PyGILState_Ensure();
ioMod = PyImport_ImportModule("io");
openedFile = PyObject_CallMethod(ioMod, "open", "ss", "foo.txt", "wb");
Py_DECREF(ioMod);
PyObject_CallMethod(openedFile, "write", "y", "Written from Python C API!\n");
PyObject_CallMethod(openedFile, "flush", NULL);
PyObject_CallMethod(openedFile, "close", NULL);
Py_DECREF(openedFile);
PyGILState_Release(gilState);
Py_Finalize();
OTHER TIPS
This page claims the API is:
PyFile_FromFd(int fd, char *name, char *mode, int buffering, char *encoding, char *newline, int closefd);
Not sure if that means it's not possible to have Python open the file from the filename, but that should be trivial to do yourself, in C.
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