Henry Huang keenhenry

The Best of the Best Practices (BOBP) Guide for Python

A "Best of the Best Practices" (BOBP) guide to developing in Python.

In General

Values

"Build tools for others that you want to be built for you." - Kenneth Reitz
"Simplicity is alway better than functionality." - Pieter Hintjens

Transforming Code into Beautiful, Idiomatic Python

Notes from Raymond Hettinger's talk at pycon US 2013 video, slides.

The code examples and direct quotes are all from Raymond's talk. I've reproduced them here for my own edification and the hopes that others will find them as handy as I have!

Looping over a range of numbers

for i in [0, 1, 2, 3, 4, 5]:

While attempting to explain JavaScript's reduce method on arrays, conceptually, I came up with the following - hopefully it's helpful; happy to tweak it if anyone has suggestions.

Intro

JavaScript Arrays have lots of built in methods on their prototype. Some of them mutate - ie, they change the underlying array in-place. Luckily, most of them do not - they instead return an entirely distinct array. Since arrays are conceptually a contiguous list of items, it helps code clarity and maintainability a lot to be able to operate on them in a "functional" way. (I'll also insist on referring to an array as a "list" - although in some languages, List is a native data type, in JS and this post, I'm referring to the concept. Everywhere I use the word "list" you can assume I'm talking about a JS Array) This means, to perform a single operation on the list as a whole ("atomically"), and to return a new list - thus making it much simpler to think about both the old list and the new one, what they contain, and

PyCon 2012 Digest

from DevOps team {rduplain,mattd,teebes}, to mobile developers at WillowTree Apps

	<!DOCTYPE html>
	<html>
	<head>
	<script data-main="usage" src="http://requirejs.org/docs/release/1.0.8/comments/require.js"></script>
	</head>
	<body>
	<p>Check your JavaScript console for output!</p>
	</body>
	</head>

	Latency Comparison Numbers
	--------------------------
	L1 cache reference 0.5 ns
	Branch mispredict 5 ns
	L2 cache reference 7 ns 14x L1 cache
	Mutex lock/unlock 25 ns
	Main memory reference 100 ns 20x L2 cache, 200x L1 cache
	Compress 1K bytes with Zippy 3,000 ns 3 us
	Send 1K bytes over 1 Gbps network 10,000 ns 10 us
	Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD

	#!/bin/bash

	export FOO=100

	python - <<END

	import os
	print "foo:", os.environ['FOO']

	END

	// --- Compiling ---
	$ wget http://download.redis.io/releases/redis-2.8.3.tar.gz
	$ tar xzvf redis-2.8.3.tar.gz
	$ cd redis-2.8.3
	$ make
	$ make install

	// --- or using yum ---
	$ rpm -Uvh http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
	$ rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm

	import shutil
	import tempfile

	from django.conf import settings
	from django.core.files.storage import FileSystemStorage
	from django.db.models import FileField
	from django.db.models.loading import get_model, get_models
	from django.test.runner import DiscoverRunner

	# supervisord - Upstarts the supervisor as service
	# Put this file into /etc/init/supervisord.conf
	# sudo service supervisord start
	# sudo service supervisord stop
	# Service gets started as root
	# Needs `pgrep` available to root

	description "Supervisord - Upstart"

	stop on runlevel [016]