My secret to high uptime:

while True:
    try:
        main()
    except:
        pass

Don’t need to activate your venv to use it.

Just use venv/bin/python my-file.py from a script or a terminal from your project root.

Walrus operator - := - envious of the C devs being able to simultaneously assign and return a value? Envy no more, we’ve got it.

If using pyenv to support multiple python versions, when creating venvs, make sure to pass --copies to it.

% python3 -m venv venv --copies

Ordinarily, venv uses symbolic links back to the current version of the python binary. A lot of tools and IDEs don’t traverse symbolic links. That flag actually copies the real binaries over to the venv.

This avoids a metric ton of hard-to-diagnose misery later on.

If you’re on Linux (or Mac), add an alias to your .bashrc:

alias activate="source env/bin/activate"

Now you can activate your venv by just running activate in the project root!

Use fewer loops and more comprehensions.

Also, for the love of $DEITY, embrace EAFP!

I forget where I originally found this and Google on my phone was unhelpful.

My favorite annoying trick is x -=- 1. It looks like it shouldn’t work because that’s not precisely a valid operator, but it functions as an increment equivalent to x += 1

It works because -= still functions are “subtract and assign”, but the second minus applies to the 1 making it -1.

You can feign immutablility on class attributes by playing with __setattr__. I don’t remember the exact way to do it, but its roughly like this:

class YourClass:
    def __setattr__(self, name, value):
        if not hasattr(self, name):
            super().__setattr__(name, value)
       else:
            # handle as you wish if the
            # attr/value already exists.
            # pass, raise, whatever

I say “feign immutability” because there are still cases in which an attr value can change, such as:

• the underlying attribute contains a list and appending to the list
• the underlying attribute is a class and modifying the class’s attributes
• pretty much anything that does “in place” changes, because so much of python is referential and has side effects.

import antigravity

Can I request a hack? How do I handle several different versions of Python installed, which one is used for pip stuff, and how sudo/running as services changes all of this.

PyPy exists. (This is news to around 95% of the community.)

If using asyncio is too impenetrable, try using Trio instead. It’s a sensibly-designed asynchronous library, to the point that you’ll find it’s easier to write non-trivial Python programs in Trio from the start, rather than bolting-on async support later.

Asyncio is just plain weird, IMO, exposing more low-level concerns than is customary for Python. Whereas Trio lets you get things done intuitively.

Not necessarily a trick that’s always useful but I always forget this.
You can get async REPL by calling python -m asyncio.

Also, old trick - in need of simple http server serving static files?
python -m http.server