Pointers? In my Python? It's more likely than you think

Learn about some of the weird and wonderful ways Python memory works!

Eli Holderness

Abstractions Beginners CPython Compiler and Interpreters Python general

See in schedule

Ever wondered about the difference between `is` and `==`, or why you might need to use `deepcopy`? Maybe you’ve been stumped by an interview question about object lifetimes, or overriding the `__eq__` method. Or, perhaps, you just really want to see some tuples behaving badly.

Join me for a tour of some of CPython’s dark memory magic and unintuitive behaviours, where we’ll find out:

- What pointers are and where you’ll see them in your code;
- What the `id` of a Python object is, and why it matters;
- How CPython can tell when you’re done using an object, and what happens next.

Python is a wonderful thing that takes all the complication of memory management away from us. We don’t have to worry about pre-allocating memory for our objects, or remember to free it once we’re done. So, given that we’re not doing it manually, how do these things happen? Do we have to care? Well, sometimes. Maybe.

In this talk, we’ll discuss what a pointer is, where they crop in in Python, and what you need to know in order to avoid getting tripped up by them. We’ll also cover the `id` of an object, how it varies between different implementations like Jython and PyPy, and why 'equal' is different from 'identical'. Finally, we’ll talk about garbage collection, what reference counting is, and how CPython knows when it’s time to get rid of unused objects.

Whether you just want to understand what’s going on under the hood without having to dive into the implementation, or you’re on the hunt for some new diabolical things to do with code (self-referential lists are only the beginning!), come along to this talk and learn about the pointers in your Python.

This talk is aimed at anyone with an interest in how Python handles objects in memory, or who’s ever been confused by side-effects popping up in their code. Absolutely no knowledge of C is required, and Python beginners are extremely welcome.

Type: Talk (30 mins); Python level: Beginner; Domain level: Beginner


Eli Holderness

Anvil

Eli has been writing Python since graduating 5 years ago, and has worked in industries ranging from telecoms to analog circuit design to biotech. Now, they're helping reshape the world of web development as a Developer Advocate at Anvil - a.k.a., being paid to build cool things and be loud online. They love Python for its accessibility, versatility and power.

In their spare time, they like to knit, play video games, and hang out with their cat.