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PEP 572
THE WALRUS OPERATOR
~
DUSTIN INGRAM
PYCON US 2019
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HI, I'M DUSTIN
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PEP 572
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PYTHON
GOVERNANCE
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BDFL
BENEVOLENT DICTATOR
FOR LIFE
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PEP
PYTHON ENHANCEMENT
PROPOSAL
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PEP 8
STYLE GUIDE
FOR PYTHON CODE
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PEP 8
STYLE GUIDE
FOR PYTHON CODE
AUTHOR: GUIDO VAN ROSSUM
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PEP 20
THE ZEN OF PYTHON
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PEP 20
THE ZEN OF PYTHON
AUTHOR: TIM PETERS
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PEP 566
METADATA FOR PYTHON
SOFTWARE PACKAGES 2.1
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PEP 566
METADATA FOR PYTHON
SOFTWARE PACKAGES 2.1
AUTHOR: DUSTIN INGRAM
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1) DRAFT
2) ACCEPTANCE
3) IMPLEMENTATION
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1) DRAFT
2) ACCEPTANCE
3) IMPLEMENTATION
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1) DRAFT
2) ACCEPTANCE
3) IMPLEMENTATION
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BDFL
DELEGATES
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PEP 572
ASSIGNMENT EXPRESSIONS
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:=
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EXAMPLES
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BALANCING
LOC AND BIG O()
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foo = [f(x), f(x)**2, f(x)**3]
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y = f(x)
foo = [y, y**2, y**3]
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foo = [y := f(x), y**2, y**3]
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AVOIDING
INEFFICIENT
COMPREHENSIONS
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results = []
for x in data:
result = f(x)
if result:
results.append(result)
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results = [
f(x) for x in data
if f(x)
]
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results = [
y for x in data
if (y := f(x))
]
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UNNECESSARY
VARIABLES IN SCOPE
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match = pattern.search(data)
if match:
do_something(match)
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if (match := pattern.search(data)):
do_something(match)
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PROCESSING
STREAMS IN CHUNKS
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chunk = file.read(8192)
while chunk:
process(chunk)
chunk = file.read(8192)
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while chunk := file.read(8192):
process(chunk)
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WHY?
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FEWER LINES
ARE BETTER
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y = f(x)
foo = [y, y**2, y**3]
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foo = [y := f(x), y**2, y**3]
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FEWER LINES
ARE MORE EFFICIENT?
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match = re.match(data)
group = match.group(1) if match else None
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group = re.match(data).group(1) if re.match(data) else None
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group = match.group(1) if (match := re.match(data)) else None
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=
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x = y = z = 0 # Yes
(z := (y := (x := 0))) # No
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a[i] = x # Yes
a[i] := x # No
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self.rest = [] # Yes
self.rest := [] # No
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x = 1, 2 # Sets x to (1, 2)
(x := 1, 2) # Sets x to 1
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total += tax # Yes
total +:= tax # No
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+:=
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PEP 572
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RECEPTION
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BACKWARDS
COMPATIBILITY
"WHERE WILL THIS WORK?"
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TEACHABILITY
"WHAT DO WE CALL THIS?"
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ATTRACTIVENESS
"IT'S JUST UGLY!"
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TIM PETERS:
"THE CURRENT PROPOSAL
WOULD HAVE ALLOWED A
MODEST BUT CLEAR IMPROVEMENT
IN QUITE A FEW BITS OF CODE."
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BARRY WARSAW:
"SINCE IT CHANGES THE SYNTAX OF
THE LANGUAGE, PEOPLE TEND TO FOCUS
ON THAT WITHOUT UNDERSTANDING
THE DEEPER SEMANTIC ISSUES."
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ŁUKASZ LANGA:
"DICTATORS SHOULD DICTATE"
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GUIDO VAN ROSSUM:
HAD TO STOP READING THE THREADS
SO HE WOULDN'T "GO INSANE"
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DICTATORS
ARE PEOPLE TOO
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MAINTAINERS
ARE PEOPLE TOO
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PEOPLE
ARE PEOPLE TOO
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QUESTIONS
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WHAT DOES THIS
MEAN FOR PYTHON?
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IT'S GOING
TO BE OK
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PEP 8000
PYTHON LANGUAGE
GOVERNANCE PROPOSAL OVERVIEW
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PEP 8001
PYTHON GOVERNANCE
VOTING PROCESS
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PEP 8002
OPEN SOURCE
GOVERNANCE SURVEY
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▸ PEP 8010 - The Technical Leader Governance Model
▸ PEP 8011 - Python Governance Model Lead by Trio of Pythonistas
▸ PEP 8012 - The Community Governance Model
▸ PEP 8013 - The External Governance Model
▸ PEP 8014 - The Commons Governance Model
▸ PEP 8015 - Organization of the Python community
▸ PEP 8016 - The Steering Council Model
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VOTE
DEC 1ST - 16TH, 2018
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PEP 8016
STEERING COUNCIL MODEL
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VOTE
JAN 21ST - FEB 4TH, 2019
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. . .
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Q&A
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WILL THIS BECOME
PART OF PYTHON?
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IT ALREADY HAS
(IN 3.8)
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BUT I DON'T LIKE IT!
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THEN DON'T
WRITE IT!
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IS GUIDO
COMING BACK?
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TO PYTHON?
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YES!
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AS BDFL?
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NOPE
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WILL THIS
HAPPEN AGAIN?
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WILL ANOTHER PEP
BE THIS CONTROVERSIAL?
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PROBABLY NOT
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WILL PEOPLE BE
NEGATIVE
ON THE INTERNET?
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¯\_(ϑ)_/¯
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THANKS!
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