Recently, the company I work for has been modernizing their codebases to mostly Python. Last week, I was tasked with looking into converting a utility program we rely on to manage some USB devices. I was quick to discover this program is highly specialized and is likely impossible to covert to Python (nor do I want to attempt it if I'm being honest). I have access to the source code for this program.
This program runs on Linux and currently compiles to an executable, not a shared object (.so).
Is binding Python to this program something that can be reasonably done? If so, I've already looked into ctypes, cffi, cython, pybind11, and writing raw C bindings, but I am lost as to what the best approach would be. If not, there is no major loss--I'll just have to call the program via subprocess and parse its output.
Thank you for your time.
Related
I have been searching for an answer for quite some time and I cannot figure out a robust solution: I have a C# application (on Unity) which needs to call some python functions and libraries. In particular, the python code needs to read a very large tabular file from C# -the equivalent of a large pandas dataframe-, avoiding writing and reading through a file if possible, because given the size it would reduce the performance.
I am a total beginner to C#/Unity, and I have given a look at the following workarounds:
IronPython: it is not an option because the last stable version is for python 2.7. My requirements are python 3.6 and higher, moving towards 3.8.
PyInstaller: it creates .exe files and not .dll. Moreover, it is not clear to me how you could call the executable from C# and pass a dataframe/2D array without writing it on disk. I am also not sure whether it can be called passing an entire input file as argument, if you really want to communicate via files.
Communication via socket: I am a bit lost about it. If this is really feasible on both python and Unity sides, I am happy to see your tutorials -especially for Unity!
Unity Python script editor: it works fine in dev mode. However, the python scripts cannot be included in the build. This: https://forum.unity.com/threads/python-for-unity-editor-only.914843/#post-8330904 seems very suboptimal for a stable build.
Thank you for any hint!
I was reading up on people who could create scripts to inject code into a Windows process, to make the running process malfunction or function in the way the injector desires. I have also seen that this is called "DLL injection", if I'm not mistaken.
I have been searching around how this is done on Python, and couldn't find a clean answer.
How is this implemented on Python? You would need Windows compatibility such as pywin32 modules, but then what from there? I have seen this done on C, but never on Python. Python was created in C so it should be possible to do this.
I've been messing around with Selenium in python, and I really want to have an existing C++ program run my python code.
Basically, my python code just finds a website, and downloads the file which afterwards my C++ program wants to open the file and do a bunch of operations on it. If I had a myPythonCode.py file, and my other C++ files (header.h, main.cpp, otherFunctions.cpp...) how would I go about running the python code from my C++ program?
Also both of my programs are console programs, and I was hoping that a user would have an uninterrupted experience running the program (for example, if the user wants to download a file while running the C++ program the terminal doesn't have to close, or open a different window to start the python program). Any help in going about this would be greatly appreciated!
It is operating system specific, and the C++11 standard does not define any functions for that (except system(3), which is in C99, and std::system in C++11). On Linux (and other POSIX systems), read Advanced Linux Programming and consider using system, or popen(3), or more probably the lower-level syscalls(2) like fork(2), execve(2), pipe(2), dup2(2), etc etc.... You may want some IPC and you may need to have some event loop around a multiplexing syscall like poll(2)
You could use some C++ frameworks like Qt or Poco (both have a process abstraction and are usable on several operating systems, even on proprietary ones from Microsoft)
If you want your C++ program to have a terminal interface on Linux, consider ncurses and/or readline
BTW, several C or C++ libraries for HTTP exist, e.g. libcurl for HTTP client side, and libonion for HTTP server side. So you might avoid your Python program and incorporate the downloading in your C++ application.
Check out the boost library which allows running python on C++ and using your C++ in python. https://www.boost.org/doc/libs/1_49_0/libs/python/doc/
Although I found many answers and discussions about this question, I am unable to find a solution particular to my situation. Here it is:
I have a main program written in FORTRAN.
I have been given a set of python scripts that are very useful.
My goal is to access these python scripts from my main FORTRAN program. Currently, I simply call the scripts from FORTRAN as such:
CALL SYSTEM ('python pyexample.py')
Data is read from .dat files and written to .dat files. This is how the python scripts and the main FORTRAN program communicate to each other.
I am currently running my code on my local machine. I have python installed with numpy, scipy, etc.
My problem:
The code needs to run on a remote server. For strictly FORTRAN code, I compile the code locally and send the executable to the server where it waits in a queue. However, the server does not have python installed. The server is being used as a number crunching station between universities and industry. Installing python along with the necessary modules on the server is not an option. This means that my “CALL SYSTEM ('python pyexample.py')” strategy no longer works.
Solution?:
I found some information on a couple of things in thread Is it feasible to compile Python to machine code?
Shedskin, Psyco, Cython, Pypy, Cpython API
These “modules”(? Not sure if that's what to call them) seem to compile python script to C code or C++. Apparently not all python features can be translated to C. As well, some of these appear to be experimental. Is it possible to compile my python scripts with my FORTRAN code? There exists f2py which converts FORTRAN code to python, but it doesn't work the other way around.
Any help would be greatly appreciated. Thank you for your time.
Vincent
PS: I'm using python 2.6 on Ubuntu
One way or another, you'll need to get the Python runtime on your server, otherwise it won't be possible to execute Python bytecode. Ignacio is on the right track with suggesting invoking libpython directly, but due to Fortran's parameter-passing conventions, it will be a lot easier for you to write a C wrapper to handle the interface between Fortran and the CPython embedding API.
Unfortunately, you're doing this the hard way -- it's a lot easier to write a Python program that can call Fortran subroutines than the other way around.
You don't want any of those. What you should do is use FORTRAN's FFI to talk with libpython and frob its API.
This question already has an answer here:
Closed 11 years ago.
Possible Duplicate:
Calling Python from Objective-C
I'm a long-time Python programmer and short-time Cocoa programmer. I'm just getting started with PyObjC and it's really amazing how easy it it is to get stuff done. That said, I wanted to try using pure ObjC for my controller with PyObjC models. I might be enjoy letting Python be Python and Objective-C be Objective-C. I figured it was worth a try, anyways.
Except I can't figure out or find anything about how to call Python from Objective-C, only the other way around. Can someone point me to any resources on this? (Maybe it's on the PyObjC site but I just don't know what I'm looking for?)
Edit: I'm most interested, at the basic level, in being able to call a Python module and get some native ObjC data types back.
There are several possible approaches. The most tempting is to use py2app to compile a loadable bundle from your python code from which you can access the principal class using NSBundle. Unfortunately, this use case hasn't gotten much love from the py2app developers, and I've found several bugs in 10.5 and 10.6, including a rather nasty memory leak when passing data from python back in to Objective-C. I wouldn't recommend using py2app at thist point.
The second approach is invert the embedding. Write a Python cocoa app and load your Objective-C code from a bundle at startup (even in main()). If you already have a large Objective-C app, this may take a bit of work. The only downside, that I'm ware of, is that you won't be able to use GC in your Objective-C code, but this is really a universal limitation in working with PyObjC.
Finally, you can instantiate a python interpreter in your Objective-C code to load your python code. This is obviously more involved, but may the best option if you already have a large Objective-C codebase into which you want to inject your python code. The main.m file from the Python-Cococa application template in Xcode is a good place to start to see this in action.
Whoops, guess I should've searched a bit more:
Calling Python from Objective-C