Using one bpython with multiple virtual environments

I finally realized that I should change the default Python REPL. There are many REPLs that offer a much better experience—ipython, bpython, and ptpython are probably the most well-known. In the past, I used ipython because I worked on many projects that involved Jupyter notebooks, so it came essentially for free whenever I installed the necessary packages.

However, in recent years, I’ve been working on a lot of projects that don’t rely on Jupyter, meaning ipython wasn’t installed by default. This meant I always had to manually install it in any virtual environment where I wanted to use it—which I didn’t like, as I prefer to keep only project-specific dependencies in a virtual environment.

As a result, I relied on the plain old python REPL, with all its shortcomings—especially the difficulty of pasting code snippets (which, thankfully, will be improved with Python 3.13).

Today, I started wondering if there was a way to use a REPL like bpython in every environment I have. You can install it once with pipx and use it everywhere, but it won’t find any packages by default. While searching online, I came across a promising post on Stack Overflow. Although the post was from 2014 and the exact approach didn’t work, with a bit of fiddling, I found a solution that seems to work. I added the following function to my .zshrc:

function bp() {
    if test -n "$VIRTUAL_ENV"
    then
        PP=".$(python -c 'import sys; print(":".join(sys.path))')" 
        PYTHONPATH=${PP} bpython "$@"
    else
        bpython "$@"
    fi
}

Now, I can simply type bp, and it will either start bpython directly or, if a virtual environment is active, it will set the PYTHONPATH to include the venv directory before starting the REPL.