I was well on my way to sending a help request about "why can I not add a path to sys.path" in an embedded python instance (that I'm adding to a c app). I have test code from *three* different methods that should add a path to the sys.path object, but none of them _seemed_ to work. I highlight that word because the way I was testing is what seems to be flawed. All three methods turn out to work, but the way I was testing appears to be flawed.

I was testing by comparing the output of Py_GetPath() before I adjusted the path, and then after I adjusted the path. It always shows the same.

On a whim, I added a call to load a quickie python script in that extra subdirectory after I adjusted the path and I was FLOORED when loaded. I've been working on this for days thinking that it wasn't working because the output of Py_GetPath() did not indicate the new path I was adding.

Question A: Is it normal that Py_GetPath() doesn't show the adjusted path?

Method 1: PySys_GetObject("path"), PyList_Insert(), PySys_SetObject() with the new object

Method 2: PyRun_SimpleString("import sys" "sys.path.append('blah')")

Method 3: Py_GetPath(),append the syspath and new path together, PySys_SetPath() with the new string

Question B: All three seem to work equally well, is there a reason to choose one over the other?

All positive guidance and suggestions are welcome. Testing C code is quoted below, as well as the sample output from running it and an strace trimmed output to show that it does appear to be loading the module. Thanks for any comments, observations, or explanations.

...Todd

py_testc:

#include

int main (int argc, char *argv[]) { char *path, *eximpath = "/etc/exim"; PyObject *syspath, *pName, *pModule;

Py_SetProgramName("application"); Py_Initialize(); if (!Py_IsInitialized()) { printf("Error initializing Python interpreter\n"); return 1; } path = Py_GetPath(); printf("Python search path is:\n%s\n", path);

syspath = PySys_GetObject("path"); if (syspath == 0) printf("Python failed to import sys\n");

printf("Adding %s\n", eximpath); pName = PyString_FromString(eximpath); if (PyList_Insert(syspath, 0, pName)) printf("Error inserting extra path into sys.path list\n"); if (PySys_SetObject("path", syspath)) printf("Error setting sys.path object\n");

pName = PyString_FromString("mod_python"); pModule = PyImport_Import(pName); Py_DECREF(pName); if (pModule == NULL) printf("Unable to import module\n"); else printf("Loaded module\n");

/* Still shows wrong path! But module still loads above. */ path = Py_GetPath(); printf("Modified Python search path is:\n%s\n", path);

Py_DECREF(syspath); Py_Finalize(); return 0; } // vim:sw=2 ts=2 expandtab

[todd@tlyons ~/python]$ ./py_test Python search path is: /usr/lib/python2.7/:/usr/lib/python2.7/plat-linux2:/usr/lib/python2.7/lib-tk:/usr/lib/python2.7/lib-old:/usr/lib/python2.7/lib-dynload Adding /etc/exim Loaded module Modified Python search path is: /usr/lib/python2.7/:/usr/lib/python2.7/plat-linux2:/usr/lib/python2.7/lib-tk:/usr/lib/python2.7/lib-old:/usr/lib/python2.7/lib-dynload

[todd@tlyons ~/python]$ strace ./py_test 2>&1 | grep mod_python stat64("/etc/exim/mod_python", 0xbf9dfa58) = -1 ENOENT (No such file or directory) open("/etc/exim/mod_python.so", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory) open("/etc/exim/mod_pythonmodule.so", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory) open("/etc/exim/mod_python.py", O_RDONLY|O_LARGEFILE) = 3 open("/etc/exim/mod_python.pyc", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory) unlink("/etc/exim/mod_python.pyc") = -1 ENOENT (No such file or directory) open("/etc/exim/mod_python.pyc", O_WRONLY|O_CREAT|O_EXCL|O_TRUNC|O_LARGEFILE, 0100644) = -1 EACCES (Permission denied)

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