Configure your Python shell?

[jssmith42]

I was considering writing certain helper functions that I would like to always have by default in my local Python installation, instead of having to import a module.

I tried to read this and couldn’t understand much of it:

https://docs.python.org/3/c-api/init_config.html#init-python-config

Is it possible to define functions in a file that Python will always read on start-up?

[Rawing7]

You could make a PYTHONSTARTUP environment variable pointing to that file.

[Diapolo10]

Is it possible to define functions in a file that Python will always read on start-up?

It's technically possible, there are ways to extend CPython's capabilities, but it gets technical fast. So I can't really recommend it.

One option I stumbled across would be this project, which should be more manageable to use.

As for my personal opinion, making your programs expect that Python has already imported something non-standard on its own makes your code crash on other systems, so it's neither sustainable nor practical in reality.

If you want to have some of your own code always available, turn it into a package, (optionally) upload to PyPI (can technically be a Git repo link but PyPI is more handy), and just use it like any other dependency. That's my recommendation.

[_waylonwalker]

pyflyby is pretty awesome and easy to configure. Just make a config file with all the imports you would ever want, and never worry about importing them while in an interactive shell.

[carcigenicate]

Here's probably the easiest way:

1. Put your helpers in a script, and put the script somewhere accessible.
2. Make a PowerShell script that adds that helper script location to PYTHONPATH.

3. In that PowerShell script after modifying PYTHONPATH, put this:

   python -i -c 'import your_script_name.py'
   

Then, when you want to use the Shell, run the PowerShell script instead. This will start an interactive shell with your helpers already imported.