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A Python Æsthetic
Video: http://pyvideo.org/video/1599/ Slides: http://rhodesmill.org/brandon/slides/2012-11-pyconca/
Video: http://pyvideo.org/video/1676/ Slides: http://rhodesmill.org/brandon/slides/2013-03-pycon/
Name the Ducks
• Well-factored Nouns
• Relentless Verbs
• Sin of Synecdoche
• Problem of Pluralization
Well-Factored Nouns
def main():! page = 'http://twitter.com/uranusjr/'! download_page(page)
Well-Factored Nouns
def main():! page = 'http://twitter.com/uranusjr/'! download_page(page)!!def download_page(page)! ... = client.get(page)
Well-Factored Nouns
def main():! page = 'http://twitter.com/uranusjr/'! download_page(page)!!def download_page(url)! page = client.get(url)
Well-Factored Nouns
def main():! page = 'http://twitter.com/uranusjr/'! download_page(page)!!def download_page(url):! page = client.get(url)! process_page(page)!!def process_page(page):! ... = page.content
Well-Factored Nouns
def main():! page = 'http://twitter.com/uranusjr/'! download_page(page)!!def download_page(url):! page = client.get(url)! process_page(page)!!def process_page(response):! page = response.content
Well-Factored Nouns
def main():! page = 'http://twitter.com/uranusjr/'! download_page(page)!!def download_page(url):! page = requests.get(url)! process_page(page)!!def process_page(response):! page = response.content
Well-Factored Nouns
def main():! url = 'http://twitter.com/uranusjr/'! download_page(url)!!def download_page(url):! response = requests.get(url)! process_page(response)!!def process_page(response):! page = response.content
Well-Factored Nouns
• Plan ahead (when you can)
• Refactor often
• Challenge yourself
Relentless Verbs
def database():! # What does this even do?!!def get_database():! # Gets an instance for me!!!def create_database():! # Creates a database and returns! # it for me!
Relentless Verbs
def database():! # What does this even do?!!def get_database():! # Gets an instance for me!!!def create_database():! # Creates a database and returns! # it for me!
Relentless Verbs
document.md5()! ! ! # Probably okay!!document.get_md5()!!document.calculate_md5()
[P]racticality beats purity.
[P]racticality beats purity.reversed(iterable)!!'a'.upper()!!
len(iterable)!!min(iterable)!
Relentless Verbs
• Functions act
• Verbose verbs can be dropped
• Practicality beats purity
Sin of Synecdoche
# In medialib.py:!def fetch_songs(urls):! ...!!# In songlib.py:!def fetch(urls):! ...
Sin of Synecdoche
# The caller has their choice:!!from songlib import fetch!fetch(...)!!# or:!!import songlib!songlib.fetch(...)
Sin of Synecdoche
• Be obvious
• Don’t repeat yourself
• Let users choose
Problem of Pluralization
>>> connections![<SQLConnection at 0xb72ff4d8>,! <SQLConnection at 0xb72ff4d0>,! <SQLConnection at 0xb72ff4f0>]!!>>> connections!{'master': <SQLConnection at 0xb72ff4d8>,! 'backup': <SQLConnection at 0xb72ff4f0>}
datum
data
datumdatum
datum
dataset
data
datumdatumdatum
data
datumdatumdatum
data
datum
datasets
datadatudatudatu
datadatudatudatu
datadatadatudatudatu
datadatudatudatu
datadataset
datadatudatudatu
datadatudatudatu
data
Anti-Plural
connection_set!connection_list!connection_dict!!def close_all(connection_seq):! ...!!def reset_all(connection_map):! ...
I still favor pluralsAnd documentation is always necessary.
Problem of Pluralization
• Plurals can be ambiguous
• There are only so many expressions
• Total anti-plural may be too much
My Problem
My Problem
def user_profile(request, username):! user = request.user! if user.is_authenticated:! if user.username == username:! # Show personal page! else:! # Show public page! else:! # Show page for anonymous user
My Problem
def user_profile(request, username):! user = request.user! if user.is_authenticated:! if user.username == username:! # Show personal page! else:! # Show public page! else:! # Show page for anonymous user
My Problem
>>> user.is_authenticated!<bound method User.is_authenticated of <User: admin>>
My Problem
def user_profile(request, username):! user = request.user! if user.is_authenticated():! if user.username == username:! # Show personal page! else:! # Show public page! else:! # Show page for anonymous user
Descriptive Boolean
# is + adjective = method!user.is_authenticated()!!!# No!!user.is_active!!# Clearly a noun.!user.activeness
Watch Out
# is + noun = variable?!>>> user.is_staff!True!!# But...!>>> '1'.isdigit!<built-in method isdigit of str object at 0x106fa63a0>
My Current Solution# is + anything = method!user.is_authenticated()!!!# WRONG!method.is_action = True!!# Considered correct (but ugly)!method.action_flag = True!!# Maybe use something else?!method.action_info = None
Python lacked booleans until 2.2.1
Maybe we can get away with it.
Similarly Problematic
# Makes more sense being a variable!request.url!!# Obviously needs processing. Okay.!document.md5()!!# ???!rectangle.left!rectangle.center
No Perfect Solution# Parentheses do not matter in Ruby!user.authenticated?!!# But things can get funky quickly!proc_obj = proc { user.authenticated? }!proc_obj.call!!# Python can be inconvenient!user.is_authenticated()!!# But obvious things stay obvious!func = user.is_authenticated!func()
FIRE QUESTIONS
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