Naming Convention in Python

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A Python Æsthetic

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Video: http://pyvideo.org/video/1599/ Slides: http://rhodesmill.org/brandon/slides/2012-11-pyconca/

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Video: http://pyvideo.org/video/1676/ Slides: http://rhodesmill.org/brandon/slides/2013-03-pycon/

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Name the Ducks • Well-factored Nouns • Relentless Verbs • Sin of Synecdoche • Problem of Pluralization

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Well-Factored Nouns def main():! page = 'http://twitter.com/uranusjr/'! download_page(page)

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Well-Factored Nouns def main():! page = 'http://twitter.com/uranusjr/'! download_page(page)! ! def download_page(page)! ... = client.get(page)

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Well-Factored Nouns def main():! page = 'http://twitter.com/uranusjr/'! download_page(page)! ! def download_page(url)! page = client.get(url)

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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

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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

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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

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Well-Factored Nouns • Plan ahead (when you can) • Refactor often • Challenge yourself

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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!

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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!

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Relentless Verbs document.md5()! ! ! # Probably okay! ! document.get_md5()! ! document.calculate_md5()

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[P]racticality beats purity.

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[P]racticality beats purity. reversed(iterable)! ! 'a'.upper()! ! len(iterable)! ! min(iterable)!

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Relentless Verbs • Functions act • Verbose verbs can be dropped • Practicality beats purity

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Sin of Synecdoche # In medialib.py:! def fetch_songs(urls):! ...! ! # In songlib.py:! def fetch(urls):! ...

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Sin of Synecdoche # The caller has their choice:! ! from songlib import fetch! fetch(...)! ! # or:! ! import songlib! songlib.fetch(...)

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Sin of Synecdoche • Be obvious • Don’t repeat yourself • Let users choose

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Problem of Pluralization >>> connections! [,! ,! ]! ! >>> connections! {'master': ,! 'backup': }

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datum data datum datum datum dataset data datum datum datum data datum datum datum data datum datasets data datu datu datu data datu datu datu data data datu datu datu data datu datu datu data dataset data datu datu datu data datu datu datu data

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Anti-Plural connection_set! connection_list! connection_dict! ! def close_all(connection_seq):! ...! ! def reset_all(connection_map):! ...

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I still favor plurals And documentation is always necessary.

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Problem of Pluralization • Plurals can be ambiguous • There are only so many expressions • Total anti-plural may be too much

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My Problem

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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

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My Problem >>> user.is_authenticated! >

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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

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No content

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Descriptive Boolean # is + adjective = method! user.is_authenticated()! ! ! # No!! user.is_active! ! # Clearly a noun.! user.activeness

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Watch Out # is + noun = variable?! >>> user.is_staff! True! ! # But...! >>> '1'.isdigit!

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No content

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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

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Python lacked booleans until 2.2.1 Maybe we can get away with it.

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Similarly Problematic # Makes more sense being a variable! request.url! ! # Obviously needs processing. Okay.! document.md5()! ! # ???! rectangle.left! rectangle.center

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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()

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FIRE QUESTIONS