Many of us have experienced a "wat" in Python - some behavior that totally mystifies us. Here is my PyCon talk on Investigating Python Wats, where we uncover some surprising implementation details of CPython, some unexpected consequences of mutability, and details of scope and name resolution.
Let's look at a common Python wat and try to figure out wat's actually happening!
We'll define a function, foo, which takes one argument, l, which has the default value of an empty list.
>>> def foo(l=[]):
... l.append('cat')
... return l
What happens when we call ...
Today, friends, we will continue to dissect functional programming concepts in Python. We're going to try to figure out what the hell is going on in this chunk of code:
>>> def make_contains_function(x):
... def contains(s):
... return x in s
... return contains
What happens when we pass make_contains_function a ...
Good morning, sinners. Today we're going to figure out what the hell is going on inside a Python expression like:
>>> reduce(lambda a, x: a + [x], things, [])
(What things is doesn't matter too much, as long as it's an iterable. We'll look at a more specific ...
I've been trying to learn how to write a function in the Python that prints two words, only two, "Hello World." I've been trying for six months. And today, friends, I've done it.
I've read so many places that you can make print statements in the ...
I love broken things, unfinished things, breaking things, unfinishing things. Broken and unfinished things allow you to see the process in which they were created; their most intimate secrets are exposed.
A week ago, inside The Metropolitan Museum of Art, my love for broken things was realized. Just ...
__builtins__ vs __builtin__Seriously, what's the difference? When you first fire up the Python interpreter, __builtins__ is in your namespace for free:
>>> globals().keys()
['__builtins__', '__name__', '__doc__', '__package__']
>>> __builtins__
<module '__builtin__' (built-in)>
But it appears to be the __builtin__ module (singular)! If you:
>>> import __builtin__
>>> __builtin__ is __builtins__
True
Hrm. So they ...
import with accio: A Dive into Bootstrapping and Python's GrammarAt Hacker School, I've been building an alternate universe Python by overwriting builtin functions and statements with Harry Potter spells. This is a thing you can do at Hacker School!
Although this project started as a joke, I've quickly descended so deeply into Python internals that I've ...
In my first five months of using Python, I would create .py files and then execute them in the terminal, like the loyal follower of LPTHW that I am. While it's certainly necessary to be able to write Python scripts and execute them from the terminal, I've learned ...
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