Python

1. 1

   Hello, Python

   Welcome. If you have never written code before, you are in the right place. Python is a programming language, which is a way to give a computer...

   VariablesPrintRepl
   20 min
2. 2

   Numbers and Strings

   Welcome back. In lesson 01 you ran your first Python file and learned that a variable is a labelled box that holds a value. Today we look at the two...

   IntegersFloatsString concatenationF-strings
   25 min
3. 3

   Asking the User a Question

   So far you have written programs that always do the same thing when you click play. Run them ten times, get the same ten answers. They are useful,...

   Input()String return typeInt() and float() conversionInteractive programs
   15 min
4. 4

   Control Flow

   Up to now your programs have run straight through, top to bottom, one line after the other. That is fine for greetings, but most useful programs need...

   If/elif/elseComparison operatorsBoolean operatorsWhile loopsFor loopsBreak and continue
   30 min
5. 5

   Lists and Tuples

   So far each variable has held a single value: one number, one string. Real programs usually need to keep a small group of related values together,...

   List creationIndexingSlicingAppendPopIteration+2
   30 min
6. 6

   Dictionaries and Sets

   Welcome back. Lists are great when order matters and you reach for items by position, but a lot of real data is organized by name: a person has an...

   Dict basicsGet with defaultIterate keysIterate valuesIterate itemsSets+1
   30 min
7. 7

   Functions

   Welcome back. So far you have used a few functions that came with Python, like print() and len(). In this lesson you are going to write your own. A...

   DefParametersDefault valuesKeyword arguments*args and **kwargsReturn values+1
   30 min
8. 8

   Comprehensions

   You already know how to write a for loop that builds a new list, dict, or set one item at a time. A comprehension is a shorter way to write that same...

   List comprehensionsDict comprehensionsSet comprehensionsConditional expressionsGenerator expressionsReadability tradeoffs
   25 min
9. 9

   Files and IO

   A program that only prints to the terminal forgets everything the moment it finishes. The next step, and the one that makes Python suddenly feel...

   Open with withReading linesWriting filesPathlib.PathJson readJson write
   30 min
10. 10

    Modules and Packages

    Up to now every program has lived in a single file. That is fine while you are learning, but real projects spread their code across many files so...

    ImportFrom importWriting your own moduleIf __name__ == "__main__"Packages__init__.py
    30 min
11. 11

    Classes and OOP

    Welcome to one of the bigger ideas in Python. So far you have used built-in tools (strings, lists, dicts, functions) to shape data. In this lesson...

    Class definition__init__Instance attributesClass attributesMethods__repr__
    35 min
12. 12

    Inheritance and Composition

    In lesson 11 you built classes from scratch. In real code, classes rarely live alone. Sometimes one class is a more specific version of another (a...

    SubclassingSuper()Method overridingCompositionWhen to choose composition
    30 min
13. 13

    Exception Handling

    You have already met errors. Every time you mistyped a name, divided by zero, or asked a list for an index that did not exist, Python stopped and...

    TryExceptElseFinallyRaiseCustom exception classes+1
    30 min
14. 14

    Iterators and Generators

    You already know how to write for item in something: from earlier lessons. In this lesson we look under the hood and find out what Python is actually...

    Iterator protocolYieldGenerator functionsGenerator expressionsLazy evaluation
    30 min
15. 15

    Decorators

    Welcome to one of Python's trickier topics. A decorator is a small wrapper you put around a function so it gains a little extra behaviour (logging,...

    Functions are objectsWrapper functions@decorator syntaxFunctools.wrapsParametrized decorators
    30 min
16. 16

    Context Managers

    Welcome back. Ever since lesson 09 you have been writing with open(...) as f: and trusting that the file gets closed when the block ends. This lesson...

    With statement__enter__ and __exit__Writing your own context managerContextlib.contextmanager
    25 min
17. 17

    Concurrency: Threads and Async

    Welcome back. So far our programs have done one thing at a time, top to bottom, and that has worked fine. The trouble starts when a program spends...

    GIL in plain languageConcurrent.futures.ThreadPoolExecutorAsyncio basicsAsync defAwaitWhen to use threads vs async
    40 min
18. 18

    Testing with pytest

    Welcome back. Up to now you have run code and checked the output with your eyes. That works for a few lines, but the moment you change anything, you...

    Test functionsAssertRunning pytestParametrizeFixtures
    35 min
19. 19

    Packaging and Deployment

    So far you have written Python that you (and only you) run by typing python something.py. This lesson is about the small, mostly-mechanical step that...

    Pyproject.tomlPip install -eConsole scriptsBuilding a wheelPublishing to PyPI
    35 min

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