The Python 3.12 embedding documentation for embedding gives this example:
#define PY_SSIZE_T_CLEAN
#include <Python.h>
int
main(int argc, char *argv[])
{
wchar_t *program = Py_DecodeLocale(argv[0], NULL);
if (program == NULL) {
fprintf(stderr, "Fatal error: cannot decode argv[0]\n");
exit(1);
}
Py_SetProgramName(program); /* optional but recommended */
Py_Initialize();
PyRun_SimpleString("from time import time,ctime\n"
"print('Today is', ctime(time()))\n");
if (Py_FinalizeEx() < 0) {
exit(120);
}
PyMem_RawFree(program);
return 0;
}
Although calling Py_SetProgramName()
is recommended, it throws a compile warning:
test01.c:12:5: warning: 'Py_SetProgramName' is deprecated [-Wdeprecated-declarations]
Py_SetProgramName(program); /* optional but recommended */
^
/opt/python/3.11/include/python3.11/pylifecycle.h:37:1: note: 'Py_SetProgramName' has been explicitly marked deprecated here
Py_DEPRECATED(3.11) PyAPI_FUNC(void) Py_SetProgramName(const wchar_t *);
^
/opt/python/3.11/include/python3.11/pyport.h:336:54: note: expanded from macro 'Py_DEPRECATED'
#define Py_DEPRECATED(VERSION_UNUSED) __attribute__((__deprecated__))
^
1 warning generated.
The resulting excecutable runs and if you add import sys
and print(sys.executable)
to the PyRun_SimpleString()
argument, the correct executable name is shown.
As this was deprecated in 3.11, and although is still recommended for 3.12, I rather get rid of the warning. How should I change the program?
Following the alternatives mentioned in the documentation for Py_SetProgramName
and succesfully merging code from Initialization with PyConfig I got this working program:
#define PY_SSIZE_T_CLEAN
#include <Python.h>
int
main(int argc, char *argv[])
{
wchar_t *program = Py_DecodeLocale(argv[0], NULL);
if (program == NULL) {
fprintf(stderr, "Fatal error: cannot decode argv[0]\n");
exit(1);
}
PyStatus status;
PyConfig config;
PyConfig_InitPythonConfig(&config);
status = PyConfig_SetString(&config, &config.program_name, program);
if (PyStatus_Exception(status)) {
goto exception;
}
status = Py_InitializeFromConfig(&config);
if (PyStatus_Exception(status)) {
goto exception;
}
PyRun_SimpleString(
"import sys\n"
"from time import time,ctime\n"
"print('Today is', ctime(time()))\n"
"print('executable:', sys.executable)\n"
);
if (Py_FinalizeEx() < 0) {
exit(120);
}
PyMem_RawFree(program);
PyConfig_Clear(&config);
return 0;
exception:
PyConfig_Clear(&config);
Py_ExitStatusException(status);
}
Afterwards I found that the dev (3.13) preview Documentation contained an updated example, which did away with the program
variable, and showed that the config
can be cleared before running the program:
#define PY_SSIZE_T_CLEAN
#include <Python.h>
int
main(int argc, char *argv[])
{
PyStatus status;
PyConfig config;
PyConfig_InitPythonConfig(&config);
status = PyConfig_SetBytesString(&config, &config.program_name, argv[0]);
if (PyStatus_Exception(status)) {
goto exception;
}
status = Py_InitializeFromConfig(&config);
if (PyStatus_Exception(status)) {
goto exception;
}
PyConfig_Clear(&config);
PyRun_SimpleString(
"import sys\n"
"from time import time,ctime\n"
"print('Today is', ctime(time()))\n"
"print('executable:', sys.executable)\n"
);
if (Py_FinalizeEx() < 0) {
exit(120);
}
return 0;
exception:
PyConfig_Clear(&config);
Py_ExitStatusException(status);
}