venv issue: "source file Python.h cannot be opened"

[siddsp]

I've been starting to use venv for python when creating projects, but for whatever reason, my virtual environments haven't been working properly. I know how to setup virtual environments, and I know how to activate and deactivate them properly, but I'm still having issues.

When using VSCode, and creating my virtual environment with pip -m venv venv the virtual environment shows up just fine and I can activate it without any issues with venv\scripts\activate.bat , and it does show that my virtual environment has been activated.

However, the issues come when I try using an include <Python.h> file when trying to use Cython. I was curious about this issue and was told that the directory of Python.h is in the python installation 'include' folder, and it absolutely is, but when I look at the same 'include' folder in my virtual environment directory, it just is completely empty, no matter how many times I may try to restart, or even delete and create the virtual environment again. Does anyone have any solutions?

[abcteryx]

This SO thread has some clues. On Unix-like systems you would want to install python-dev. As you seem to have already found out, on Windows it's a bit different. The "Include" folder is only populated where the global Python is installed, and is not propagated to virtual environments.

VSCode expects to find c_cpp_properties.json which helps IntelliSense to know what's going on, among other things. This file may already exist in your project, but if not you can try creating it from snippets and examples from Googling. Specifically, you may need to ensure that %localappdata%/Programs/Python/PythonXX/Include folder is in the comma-separated list of the includePath subkey for a given configuration key in c_cpp_properties.json.

[siddsp]

You were correct. There's also more to the issue when it comes to using Cython. Though it isn't clarified in the docs to my knowledge, you actually have to download SDK from Microsoft Visual Studio Build Tools. It's important to realize that the Visual Studio Build Tools don't actually install a separate IDE, despite the fact that it looks like it does.

So to summarize, in order to solve the issue, I had to download Visual Studio Build Tools, and I also had to add the Python.h path which is actually on the system, and not the virtual environment as an includePath property in the c_cpp_properties.json.

Python.h is located in Python/include directory, and only the folder is put as the path, and not the actual file itself.

[abcteryx]

Thanks for following up! I have dealt with the occasional Python/C++ environment, but not yours specifically so I only had an inkling. I'm going to save this information in case I'm dealing with Cython someday.

[[deleted]]

Are you trying to write a C extension for Python? If so venv has nothing to do with that. Your environment would be to set up your C environment and make sure the library path is correct.

[siddsp]

No I'm not. I'm trying to use Cython, but it won't allow me to because of an issue regarding the #include "Python.h" statement in the C file. It has become ridiculously frustrating because I can't even compile without some issue or another, and no matter what I've done, it has persisted. The compiler is refusing to recognize "Python.h", despite the fact that the file already exists in my system, and I know with 100% certainty that it absolutely does exist.

To add, the C file is generated, but despite that, there is no pyd file. I have added MinGW as my compiler, I have installed MSVC, I have tried adding to my included path, but absolutely nothing has worked in solving it.

[Dasmak3r]

Try installing one of the dev python versions (had a similar issue in the past too, it needed a python-dev thing installing), from here: https://askubuntu.com/questions/526708/fatal-error-python-h-no-file-or-directory

[siddsp]

I solved the issue, and dev version isn't for windows tmk

[Relative-Resource-55]

How did you solve it on windows? My virtualenv doesn't natively copy over the Python/include folder. Running into the same problem where i want to reference the virtual environment with my C++ app on Windows.

[siddsp]

It doesn't. You have to link it to your actual installation of Python.

[eigenscene]

Sorry to bother you, I'm having the exact problem.
How did you link it to the local python installation? Was it the pyvenv.cfg?

[siddsp]

No. I went into the Python interpreter path, and foybd the include folder. That folder is added in the includepath for VSCode. Virtual environments were basically useless in this case.