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Python Peculiarities

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noamt

This document discusses several Python peculiarities and quirks through examples of code snippets. Some key points covered include: - Importing * can override expected values - Default arguments are evaluated once at compile time - Built-in functions like str behave differently on integers vs other objects - Special modules and future imports can enable unusual syntax as easter eggs - Implicit variables like _ can cause unexpected behavior - Indexing issues can arise from iterating over lists in certain ways The examples serve to illustrate subtle behaviors in Python and emphasize writing clear and intentional code over clever tricks that may confuse others or cause bugs. Readability, commenting, and avoiding imports of all symbols are suggested.

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Python Peculiarities Noam Tenne
$WHOAMI Hacking around for the past ~15 years @NoamTenne http://blog.10ne.org Best company ever!
$WHOAMI Hacking around for the past ~15 years @NoamTenne http://blog.10ne.org Best company ever! We’re hiring!
$WHOAMI github.com/noamt “Cafe Bots” podcast together with Yoav Luft and Tom Kaminski
How this works
How this works • 1 entertaining dude at your service
How this works • 1 entertaining dude at your service •We review puzzles
How this works • 1 entertaining dude at your service •We review puzzles •You vote for the correct answer
First Rule!
The Princess Py name = "Inigo Montoya" victim = "my father" consequence = "die" from os import * print("Hello, my name is %s. You killed %s, prepare to %s" % (name, victim, consequence)) https://codegolf.stackexchange.com/a/11467
The Princess Py name = "Inigo Montoya" victim = "my father" consequence = "die" from os import * print("Hello, my name is %s. You killed %s, prepare to %s" % (name, victim, consequence)) 1. Hello, my name is posix. You killed my father, prepare to die
 2. Hello, my name is Inigo Montoya. You killed my father, prepare to die
 3. Hello, my name is <built-in function name>. You killed my father, prepare to die
 4. SyntaxError: invalid syntax https://codegolf.stackexchange.com/a/11467
The Princess Py name = "Inigo Montoya" victim = "my father" consequence = "die" from os import * print("Hello, my name is %s. You killed %s, prepare to %s" % (name, victim, consequence)) 1. Hello, my name is posix. You killed my father, prepare to die
 2. Hello, my name is Inigo Montoya. You killed my father, prepare to die
 3. Hello, my name is <built-in function name>. You killed my father, prepare to die
 4. SyntaxError: invalid syntax https://codegolf.stackexchange.com/a/11467
Python Peculiarities
Python Peculiarities
What’s going on? ... from os import * ... This guy
What’s going on? ... from os import * ... This guy Imports this guy
What’s going on? ... from os import * ... name = "Inigo Montoya" This guy Imports this guy And overrides this guy
How do we fix it? Don’t use import * !
Floating Votes >>> number_of_votes = 5 >>> number_of_votes.__str__() '5' >>> 5.__str__() http://blog.brush.co.nz/2008/01/ten-python-quirkies/
Floating Votes >>> number_of_votes = 5 >>> number_of_votes.__str__() '5' >>> 5.__str__() 1. 5
 2. 5.0
 3. <method-wrapper '__str__' of int object at 0x1054e5b50>
 4. SyntaxError: invalid syntax http://blog.brush.co.nz/2008/01/ten-python-quirkies/
Floating Votes >>> number_of_votes = 5 >>> number_of_votes.__str__() '5' >>> 5.__str__() 1. 5
 2. 5.0
 3. <method-wrapper '__str__' of int object at 0x1054e5b50>
 4. SyntaxError: invalid syntax http://blog.brush.co.nz/2008/01/ten-python-quirkies/
Python Peculiarities
Python Peculiarities
What’s going on? >>> number_of_votes = 5 >>> number_of_votes.__str__() '5' >>> 5.__str__()
What’s going on? >>> number_of_votes = 5 >>> number_of_votes.__str__() '5' >>> 5.__str__() What is this?
How do we fix it? Help the parser!
 Use parentheses! >>> (5).__str__()
How do we fix it? Prefer core methods over attributes >>> str(5)
It’s All Your Default def func(A=[]): A.append(42); return A print(func()) print(func()) http://blog.brush.co.nz/2008/01/ten-python-quirkies/
It’s All Your Default def func(A=[]): A.append(42); return A print(func()) print(func()) 1. []n[]
 2. [42]n[42] 3. [42]n[84]
 4. [42]n[42,42] http://blog.brush.co.nz/2008/01/ten-python-quirkies/
It’s All Your Default def func(A=[]): A.append(42); return A print(func()) print(func()) 1. []n[]
 2. [42]n[42] 3. [42]n[84]
 4. [42]n[42,42] http://blog.brush.co.nz/2008/01/ten-python-quirkies/
Python Peculiarities
Python Peculiarities
What’s going on? def func(A=[]): A.append(42); return A
What’s going on? def func(A=[]): A.append(42); return A Default methods evaluated once at compile time
Uncle Barry from __future__ import barry_as_FLUFL print(42 != 42) https://stackoverflow.com/q/4007289/198825
Uncle Barry from __future__ import barry_as_FLUFL print(42 != 42) 1. SyntaxError: invalid syntax
 2. True 3. False
 4. 84 https://stackoverflow.com/q/4007289/198825
Uncle Barry from __future__ import barry_as_FLUFL print(42 != 42) 1. SyntaxError: invalid syntax
 2. True 3. False
 4. 84 https://stackoverflow.com/q/4007289/198825
Python Peculiarities
Python Peculiarities
What’s going on? from __future__ import barry_as_FLUFL PEP 401 -- BDFL Retirement
What’s going on? from __future__ import barry_as_FLUFL Replaces != with <>PEP 401 -- BDFL Retirement
How do we fix it? print(42 != 42) print(42 <> 42) Change To
How do we fix it? -or- Don’t use silly modules! print(42 != 42) print(42 <> 42) Change To
The Future! from __future__ import braces exec("if (input() > 0) {nprint 'it's the future!';n}") https://codegolf.stackexchange.com/a/11450
The Future! from __future__ import braces exec("if (input() > 0) {nprint 'it's the future!';n}") 1. Prints Nothing
 2. Prints “it’s the future!”
 3. SyntaxError: invalid syntax
 4. SyntaxError: not a chance https://codegolf.stackexchange.com/a/11450
The Future! from __future__ import braces exec("if (input() > 0) {nprint 'it's the future!';n}") 1. Prints Nothing
 2. Prints “it’s the future!”
 3. SyntaxError: invalid syntax
 4. SyntaxError: not a chance https://codegolf.stackexchange.com/a/11450
Python Peculiarities
Python Peculiarities
What’s going on? from __future__ import braces An easter egg
Python has many fun easter eggs!
Python has many fun easter eggs! import __hello__
Python has many fun easter eggs! import this import __hello__
Python has many fun easter eggs! import this import __hello__ import antigravity
Commaleon list_a = [1, 3, 3, 7], list_b = [1, 3, 3, 7] list_a.extend(list_b) print(list_a) http://bit.ly/2r7yZwY
Commaleon list_a = [1, 3, 3, 7], list_b = [1, 3, 3, 7] list_a.extend(list_b) print(list_a) 1. [[1, 3, 3, 7], 1, 3, 3, 7]
 2. [1, 3, 3, 7, 1, 3, 3, 7]
 3. [[1, 3, 3, 7], [1, 3, 3, 7]]
 4. AttributeError http://bit.ly/2r7yZwY
Commaleon list_a = [1, 3, 3, 7], list_b = [1, 3, 3, 7] list_a.extend(list_b) print(list_a) 1. [[1, 3, 3, 7], 1, 3, 3, 7]
 2. [1, 3, 3, 7, 1, 3, 3, 7]
 3. [[1, 3, 3, 7], [1, 3, 3, 7]]
 4. AttributeError http://bit.ly/2r7yZwY
Python Peculiarities
Python Peculiarities
What’s going on? list_a = [1, 3, 3, 7], list_b = [1, 3, 3, 7] list_a.extend(list_b) print(list_a)
What’s going on? list_a = [1, 3, 3, 7], list_b = [1, 3, 3, 7] list_a.extend(list_b) print(list_a) list_a is now
 a tuple
What’s going on? list_a = [1, 3, 3, 7], list_b = [1, 3, 3, 7] list_a.extend(list_b) print(list_a) list_a is now
 a tuple Tupples have no extend attribute
How do we fix it? Use static analysis rules
Johnny Cache >>> 1*2 2 >>> _*3 6 >>> print(_*4) 24 >>> print(_*5) http://bit.ly/2rfOMhe
Johnny Cache >>> 1*2 2 >>> _*3 6 >>> print(_*4) 24 >>> print(_*5) 1. SyntaxError 2. AttributeError
 3. 108
 4. 30 http://bit.ly/2rfOMhe
Johnny Cache >>> 1*2 2 >>> _*3 6 >>> print(_*4) 24 >>> print(_*5) 1. SyntaxError 2. AttributeError
 3. 108
 4. 30 http://bit.ly/2rfOMhe
Python Peculiarities
Python Peculiarities
What’s going on? >>> 1*2 2 >>> _*3 6 >>> print(_*4) 24 >>> print(_*5)
What’s going on? _ accesses last returned value >>> 1*2 2 >>> _*3 6 >>> print(_*4) 24 >>> print(_*5)
What’s going on? _ accesses last returned value Return value of print is None >>> 1*2 2 >>> _*3 6 >>> print(_*4) 24 >>> print(_*5)
Multiplication Complication multiplication = [] for i in range(10): multiplication.append(i * ++i) for multiplication[i] in multiplication: print(multiplication[i]) https://codegolf.stackexchange.com/a/11480
Multiplication Complication multiplication = [] for i in range(10): multiplication.append(i * ++i) for multiplication[i] in multiplication: print(multiplication[i]) 1. 0, 1, 4, 9, 16, 25, 36, 49, 64, 81
 2. 0, 1, 4, 9, 16, 25, 36, 49, 64, 64
 3. SyntaxError
 4. 0, 2, 6, 12, 20, 30, 42, 56, 72, 90 https://codegolf.stackexchange.com/a/11480
Multiplication Complication multiplication = [] for i in range(10): multiplication.append(i * ++i) for multiplication[i] in multiplication: print(multiplication[i]) 1. 0, 1, 4, 9, 16, 25, 36, 49, 64, 81
 2. 0, 1, 4, 9, 16, 25, 36, 49, 64, 64
 3. SyntaxError
 4. 0, 2, 6, 12, 20, 30, 42, 56, 72, 90 https://codegolf.stackexchange.com/a/11480
Python Peculiarities
Python Peculiarities
What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i)
What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation
What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] for multiplication[i] in multiplication: Assigns each element to index 9
What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] for multiplication[i] in multiplication: Assigns each element to index 9 [0, 1, 4, 9, 16, 25, 36, 49, 64, 0]
What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] for multiplication[i] in multiplication: Assigns each element to index 9 [0, 1, 4, 9, 16, 25, 36, 49, 64, 1]
What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] for multiplication[i] in multiplication: Assigns each element to index 9 [0, 1, 4, 9, 16, 25, 36, 49, 64, 4]
What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] for multiplication[i] in multiplication: Assigns each element to index 9 [0, 1, 4, 9, 16, 25, 36, 49, 64, 64]
What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] for multiplication[i] in multiplication: Assigns each element to index 9
Some take-aways
Some take-aways 1. Write readable code
Some take-aways 1. Write readable code 2.Document/Comment your tricks and hacks
Some take-aways 1. Write readable code 2.Document/Comment your tricks and hacks 3.Use static analysis and a good IDE
Some take-aways 1. Write readable code 2.Document/Comment your tricks and hacks 3.Use static analysis and a good IDE 4.RTFM!
Positive Feedback? @NoamTenne noam@10ne.org Negative Feedback? /dev/null
Queries?
Thanks!

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Python Peculiarities

  • 2. $WHOAMI Hacking around for the past ~15 years @NoamTenne http://blog.10ne.org Best company ever!
  • 3. $WHOAMI Hacking around for the past ~15 years @NoamTenne http://blog.10ne.org Best company ever! We’re hiring!
  • 4. $WHOAMI github.com/noamt “Cafe Bots” podcast together with Yoav Luft and Tom Kaminski
  • 6. How this works • 1 entertaining dude at your service
  • 7. How this works • 1 entertaining dude at your service •We review puzzles
  • 8. How this works • 1 entertaining dude at your service •We review puzzles •You vote for the correct answer
  • 10. The Princess Py name = "Inigo Montoya" victim = "my father" consequence = "die" from os import * print("Hello, my name is %s. You killed %s, prepare to %s" % (name, victim, consequence)) https://codegolf.stackexchange.com/a/11467
  • 11. The Princess Py name = "Inigo Montoya" victim = "my father" consequence = "die" from os import * print("Hello, my name is %s. You killed %s, prepare to %s" % (name, victim, consequence)) 1. Hello, my name is posix. You killed my father, prepare to die
 2. Hello, my name is Inigo Montoya. You killed my father, prepare to die
 3. Hello, my name is <built-in function name>. You killed my father, prepare to die
 4. SyntaxError: invalid syntax https://codegolf.stackexchange.com/a/11467
  • 12. The Princess Py name = "Inigo Montoya" victim = "my father" consequence = "die" from os import * print("Hello, my name is %s. You killed %s, prepare to %s" % (name, victim, consequence)) 1. Hello, my name is posix. You killed my father, prepare to die
 2. Hello, my name is Inigo Montoya. You killed my father, prepare to die
 3. Hello, my name is <built-in function name>. You killed my father, prepare to die
 4. SyntaxError: invalid syntax https://codegolf.stackexchange.com/a/11467
  • 15. What’s going on? ... from os import * ... This guy
  • 16. What’s going on? ... from os import * ... This guy Imports this guy
  • 17. What’s going on? ... from os import * ... name = "Inigo Montoya" This guy Imports this guy And overrides this guy
  • 18. How do we fix it? Don’t use import * !
  • 19. Floating Votes >>> number_of_votes = 5 >>> number_of_votes.__str__() '5' >>> 5.__str__() http://blog.brush.co.nz/2008/01/ten-python-quirkies/
  • 20. Floating Votes >>> number_of_votes = 5 >>> number_of_votes.__str__() '5' >>> 5.__str__() 1. 5
 2. 5.0
 3. <method-wrapper '__str__' of int object at 0x1054e5b50>
 4. SyntaxError: invalid syntax http://blog.brush.co.nz/2008/01/ten-python-quirkies/
  • 21. Floating Votes >>> number_of_votes = 5 >>> number_of_votes.__str__() '5' >>> 5.__str__() 1. 5
 2. 5.0
 3. <method-wrapper '__str__' of int object at 0x1054e5b50>
 4. SyntaxError: invalid syntax http://blog.brush.co.nz/2008/01/ten-python-quirkies/
  • 24. What’s going on? >>> number_of_votes = 5 >>> number_of_votes.__str__() '5' >>> 5.__str__()
  • 25. What’s going on? >>> number_of_votes = 5 >>> number_of_votes.__str__() '5' >>> 5.__str__() What is this?
  • 26. How do we fix it? Help the parser!
 Use parentheses! >>> (5).__str__()
  • 27. How do we fix it? Prefer core methods over attributes >>> str(5)
  • 28. It’s All Your Default def func(A=[]): A.append(42); return A print(func()) print(func()) http://blog.brush.co.nz/2008/01/ten-python-quirkies/
  • 29. It’s All Your Default def func(A=[]): A.append(42); return A print(func()) print(func()) 1. []n[]
 2. [42]n[42] 3. [42]n[84]
 4. [42]n[42,42] http://blog.brush.co.nz/2008/01/ten-python-quirkies/
  • 30. It’s All Your Default def func(A=[]): A.append(42); return A print(func()) print(func()) 1. []n[]
 2. [42]n[42] 3. [42]n[84]
 4. [42]n[42,42] http://blog.brush.co.nz/2008/01/ten-python-quirkies/
  • 33. What’s going on? def func(A=[]): A.append(42); return A
  • 34. What’s going on? def func(A=[]): A.append(42); return A Default methods evaluated once at compile time
  • 35. Uncle Barry from __future__ import barry_as_FLUFL print(42 != 42) https://stackoverflow.com/q/4007289/198825
  • 36. Uncle Barry from __future__ import barry_as_FLUFL print(42 != 42) 1. SyntaxError: invalid syntax
 2. True 3. False
 4. 84 https://stackoverflow.com/q/4007289/198825
  • 37. Uncle Barry from __future__ import barry_as_FLUFL print(42 != 42) 1. SyntaxError: invalid syntax
 2. True 3. False
 4. 84 https://stackoverflow.com/q/4007289/198825
  • 40. What’s going on? from __future__ import barry_as_FLUFL PEP 401 -- BDFL Retirement
  • 41. What’s going on? from __future__ import barry_as_FLUFL Replaces != with <>PEP 401 -- BDFL Retirement
  • 42. How do we fix it? print(42 != 42) print(42 <> 42) Change To
  • 43. How do we fix it? -or- Don’t use silly modules! print(42 != 42) print(42 <> 42) Change To
  • 44. The Future! from __future__ import braces exec("if (input() > 0) {nprint 'it's the future!';n}") https://codegolf.stackexchange.com/a/11450
  • 45. The Future! from __future__ import braces exec("if (input() > 0) {nprint 'it's the future!';n}") 1. Prints Nothing
 2. Prints “it’s the future!”
 3. SyntaxError: invalid syntax
 4. SyntaxError: not a chance https://codegolf.stackexchange.com/a/11450
  • 46. The Future! from __future__ import braces exec("if (input() > 0) {nprint 'it's the future!';n}") 1. Prints Nothing
 2. Prints “it’s the future!”
 3. SyntaxError: invalid syntax
 4. SyntaxError: not a chance https://codegolf.stackexchange.com/a/11450
  • 49. What’s going on? from __future__ import braces An easter egg
  • 50. Python has many fun easter eggs!
  • 51. Python has many fun easter eggs! import __hello__
  • 52. Python has many fun easter eggs! import this import __hello__
  • 53. Python has many fun easter eggs! import this import __hello__ import antigravity
  • 54. Commaleon list_a = [1, 3, 3, 7], list_b = [1, 3, 3, 7] list_a.extend(list_b) print(list_a) http://bit.ly/2r7yZwY
  • 55. Commaleon list_a = [1, 3, 3, 7], list_b = [1, 3, 3, 7] list_a.extend(list_b) print(list_a) 1. [[1, 3, 3, 7], 1, 3, 3, 7]
 2. [1, 3, 3, 7, 1, 3, 3, 7]
 3. [[1, 3, 3, 7], [1, 3, 3, 7]]
 4. AttributeError http://bit.ly/2r7yZwY
  • 56. Commaleon list_a = [1, 3, 3, 7], list_b = [1, 3, 3, 7] list_a.extend(list_b) print(list_a) 1. [[1, 3, 3, 7], 1, 3, 3, 7]
 2. [1, 3, 3, 7, 1, 3, 3, 7]
 3. [[1, 3, 3, 7], [1, 3, 3, 7]]
 4. AttributeError http://bit.ly/2r7yZwY
  • 59. What’s going on? list_a = [1, 3, 3, 7], list_b = [1, 3, 3, 7] list_a.extend(list_b) print(list_a)
  • 60. What’s going on? list_a = [1, 3, 3, 7], list_b = [1, 3, 3, 7] list_a.extend(list_b) print(list_a) list_a is now
 a tuple
  • 61. What’s going on? list_a = [1, 3, 3, 7], list_b = [1, 3, 3, 7] list_a.extend(list_b) print(list_a) list_a is now
 a tuple Tupples have no extend attribute
  • 62. How do we fix it? Use static analysis rules
  • 63. Johnny Cache >>> 1*2 2 >>> _*3 6 >>> print(_*4) 24 >>> print(_*5) http://bit.ly/2rfOMhe
  • 64. Johnny Cache >>> 1*2 2 >>> _*3 6 >>> print(_*4) 24 >>> print(_*5) 1. SyntaxError 2. AttributeError
 3. 108
 4. 30 http://bit.ly/2rfOMhe
  • 65. Johnny Cache >>> 1*2 2 >>> _*3 6 >>> print(_*4) 24 >>> print(_*5) 1. SyntaxError 2. AttributeError
 3. 108
 4. 30 http://bit.ly/2rfOMhe
  • 68. What’s going on? >>> 1*2 2 >>> _*3 6 >>> print(_*4) 24 >>> print(_*5)
  • 69. What’s going on? _ accesses last returned value >>> 1*2 2 >>> _*3 6 >>> print(_*4) 24 >>> print(_*5)
  • 70. What’s going on? _ accesses last returned value Return value of print is None >>> 1*2 2 >>> _*3 6 >>> print(_*4) 24 >>> print(_*5)
  • 71. Multiplication Complication multiplication = [] for i in range(10): multiplication.append(i * ++i) for multiplication[i] in multiplication: print(multiplication[i]) https://codegolf.stackexchange.com/a/11480
  • 72. Multiplication Complication multiplication = [] for i in range(10): multiplication.append(i * ++i) for multiplication[i] in multiplication: print(multiplication[i]) 1. 0, 1, 4, 9, 16, 25, 36, 49, 64, 81
 2. 0, 1, 4, 9, 16, 25, 36, 49, 64, 64
 3. SyntaxError
 4. 0, 2, 6, 12, 20, 30, 42, 56, 72, 90 https://codegolf.stackexchange.com/a/11480
  • 73. Multiplication Complication multiplication = [] for i in range(10): multiplication.append(i * ++i) for multiplication[i] in multiplication: print(multiplication[i]) 1. 0, 1, 4, 9, 16, 25, 36, 49, 64, 81
 2. 0, 1, 4, 9, 16, 25, 36, 49, 64, 64
 3. SyntaxError
 4. 0, 2, 6, 12, 20, 30, 42, 56, 72, 90 https://codegolf.stackexchange.com/a/11480
  • 76. What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i)
  • 77. What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation
  • 78. What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
  • 79. What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] for multiplication[i] in multiplication: Assigns each element to index 9
  • 80. What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] for multiplication[i] in multiplication: Assigns each element to index 9 [0, 1, 4, 9, 16, 25, 36, 49, 64, 0]
  • 81. What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] for multiplication[i] in multiplication: Assigns each element to index 9 [0, 1, 4, 9, 16, 25, 36, 49, 64, 1]
  • 82. What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] for multiplication[i] in multiplication: Assigns each element to index 9 [0, 1, 4, 9, 16, 25, 36, 49, 64, 4]
  • 83. What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] for multiplication[i] in multiplication: Assigns each element to index 9 [0, 1, 4, 9, 16, 25, 36, 49, 64, 64]
  • 84. What’s going on? multiplication = [] for i in range(10): multiplication.append(i * ++i) Not a valid operation [0, 1, 4, 9, 16, 25, 36, 49, 64, 81] for multiplication[i] in multiplication: Assigns each element to index 9
  • 86. Some take-aways 1. Write readable code
  • 87. Some take-aways 1. Write readable code 2.Document/Comment your tricks and hacks
  • 88. Some take-aways 1. Write readable code 2.Document/Comment your tricks and hacks 3.Use static analysis and a good IDE
  • 89. Some take-aways 1. Write readable code 2.Document/Comment your tricks and hacks 3.Use static analysis and a good IDE 4.RTFM!