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AUSTIN PYTHON MEETUP
AUGUST 2018
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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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BDFL
DELEGATES
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1) DRAFT
2) ACCEPTANCE
3) IMPLEMENTATION
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PEP 572
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:=
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PROBLEMS
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match = pattern.search(data)
if match is not None:
do_something(match)
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chunk = file.read(8192)
while chunk:
process(chunk)
chunk = file.read(8192)
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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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results = []
for x in data:
result = f(x)
if result is not None:
results.append(result)
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filtered_data = [
f(x) for x in data
if f(x) is not None
]
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SOLUTIONS
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match = pattern.search(data)
if match is not None:
do_something(match)
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if (match := pattern.search(data)) is not None:
do_something(match)
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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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foo = [f(x), f(x)**2, f(x)**3]
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foo = [y := f(x), y**2, y**3]
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results = []
for x in data:
result = f(x)
if result is not None:
results.append(result)
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filtered_data = [
f(x) for x in data
if f(x) is not None
]
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filtered_data = [
y for x in data
if (y := f(x)) is not None
]
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WHY?
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LESS LINES
ARE BETTER
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foo = [y := f(x), y**2, y**3]
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y = f(x)
foo = [y, y**2, y**3]
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LESS 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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SCOPE
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foo = 'foo'
if (foo := 'bar') is not None:
do_something(...)
print(foo)
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EXCEPTIONS!
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if any((comment := line).startswith('#') for line in lines):
print("First comment:", comment)
else:
print("There are no comments")
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if all((nonblank := line).strip() == '' for line in lines):
print("All lines are blank")
else:
print("First non-blank line:", nonblank)
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total = 0
partial_sums = [total := total + v for v in values]
print("Total:", total)
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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
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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= VS. ==
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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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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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WILL THIS BECOME
PART OF PYTHON?
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PROBABLY
(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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PROBABLY NOT
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WILL THIS
HAPPEN AGAIN?
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PROBABLY NOT
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¯\_(ϑ)_/¯
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THANKS!