将Python嵌入C ++

Question

If this question could be worded better/needs to be split into many questions, please alert me

I need to package Python scripts in order to ship them as single-executables (ideally), or single-executables with supporting files (non-ideally).

I have seen py2app and py2exe. They do not fit my requirements, as I am looking for a single method to do this, and in the future may need to have the packaged scripts interact with the executable that they are being run from.

What is the best way to go about this? The scripts which I would be embedding may even require multiple files, which complicates matters I'm sure.

If I wanted to use an interpreter other than CPython (ie: PyPy or Stackless) in the future, would the process be different (other than API calls in the C++ executable)?

Does Python have to be installed on the computers which would be running the package, or does embedding Python mean that it is fully embedded? I saw on the Python Wiki something about Py_SetPythonHome() , which would indicate to me that it needs Python (or at least its libraries) to be installed. Am I correct?

Answer 1

PyInstaller with the --onefile option will put everything inside a single file, though it will take a little more time to startup. I'm afraid it's not compatible with PyPy, but it should not be so tricky to get it working using Stackless.

Good luck!

Answer 2

Are you sure that you need to embed the Python files?

I ask because you mention you want to package the Python files as single executables. Couldn't you install Python on the target machine and since Python scripts are executables on their own, you would only need something to kick them off. A master python script could kick off all the rest of the scripts.

Otherwise you should look in C++ what can run a Python script. Then have the master python script run all the other scripts.

Answer 3

Yes you can!

The easiest is with newest Python3 <OS> <arch> embeddable zip file , which contains .so/.dll and all modules.

Instructions are here: https://docs.python.org/3/extending/embedding.html

#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");
    Py_Finalize();
    PyMem_RawFree(program);
    return 0;
}

The trickier part is communication between your C++ code and Python code.

If you only have to pass a few strings back and forth, that's trivial, but if you want a very tight integration, then you'll probably need a few of these:

• create a Python module in (C++ code, C ABI) and inject it -- that means Python will be able to run import yourmod; yourmod.yourfunc(...) import yourmod; yourmod.yourfunc(...) which will run your C++ custom code and/or
• resolve and call Python functions from C++ (the inverse) https://stackoverflow.com/a/3310608/705086

Single executable

If you cannot have an installer, and really do not wish to have a bunch of .DLL/.so/etc it's described eg here Merge DLL into EXE? and it's ABI-specific, there will be one way for Windows, another Linux, etc, and you may have to override Python's import machinery (so that it doesn't look for dll/so in the file system) -- at this point, you may as well use PyInstaller or extend/merge PyInstaller with your application. Please research https://github.com/pyinstaller/pyinstaller/tree/develop/bootloader/src and evaluate how hard that might be

PyPy

Simple embedding is possisble http://doc.pypy.org/en/latest/embedding.html but single-file embedding is not. You could hack PyPy source and build custom embeddable object, but you'd be the first to do so :)

Stackless

Should be as simple as regular CPythion