Starting out
What Python actually is, what happens when you run a file, and how to read the error you are certainly about to get.
3 of 3 written
Python, from zero
Every idea in the language built up from nothing, and every line on every page really ran.
Where this stands
50 of 50 lessons written. The bar on every card below is counted from the lesson files that exist, not from a number I typed. A lesson that is planned and unwritten says so on its own page too.
- 472 Python panels, every one executed by Python 3.14.7 during this build
- 1165 assertions, all passing, or this build would have refused to write
- 82 panels that raise on purpose, across 27 distinct exception types, each showing the traceback the interpreter really produced
- 12 listings shown but not run, each stating why on the panel itself
- No network at read time, and nothing pip-installed: everything is the standard library
The core data types
Numbers, text, and the four containers almost every Python program is built out of.
6 of 6 written
Control flow
Branching, looping, comprehensions, and the pattern matching added to the language recently.
4 of 4 written
Functions
Arguments, the mutable-default trap, scope and closures: the machinery behind every abstraction later in the course.
5 of 5 written
Modules and environments
How a program becomes more than one file, how Python finds it, and why every project gets its own environment.
3 of 3 written
Errors, properly
Raising and catching exceptions on purpose, writing your own, and the with statement that guarantees cleanup.
3 of 3 written
Files and data
Reading and writing real files, the text encoding problem, and the two data formats you will meet constantly.
3 of 3 written
Objects and classes
What a class is for, the dunder methods that make your type behave like a built-in, and why composition usually beats inheritance.
5 of 5 written
Iteration
The protocol behind every for loop, generators that produce values lazily, and the itertools that do it correctly for you.
3 of 3 written
Decorators and typing
Functions that take and return functions, the standard library built on that idea, and type hints that catch mistakes before you run anything.
3 of 3 written
Testing
Proving your code does what you claim, with the library that ships in the box.
2 of 2 written
Concurrency
Threads and what the GIL actually blocks, real parallelism with processes, and async for waiting on thousands of things at once.
3 of 3 written
How Python runs
The bytecode your code compiles to, how memory and references really behave, and measuring instead of guessing.
3 of 3 written
The deep end
The protocols underneath properties and ORMs, metaclasses and why you probably should not, and the C boundary.
2 of 2 written
Shipping it
Turning a folder of scripts into something another person can install and run, and one project built end to end.
2 of 2 written