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Python

Declaration, Initialization & Assignment

  • Swap two variables using tuple
# 👎 longhand
temp = a
a = b
b = temp

# 👍 shorthand
a, b = b, a

Expressions

  • Chained comparisons for one-direction multiple comparisons
# 👎 longhand
if a > 1 and a < 9

# 👍 shorthand
if 1 < a < 9
  • Check multiple flags w/ same value
# 👎 longhand
if a == 1 or b == 1 or c == 1:

# 👍 shorthand
if 1 in (a, b, c):
  • Check multiple flags for truthiness/falsiness
if a or b or c:

if(any(a, b, c)):

Function

  • Return multiple values using tuple
def test():
    return 'abc', 100
  • Use lambda for single statement functions
# 👎 longhand
def subtract(x, y): 
    return x - y

# 👍 shorthand
subtract = lambda x, y : x - y
  • Use @cache decorator from functools library to cache repeating expensive computations, esp. in recursive functions [Python3.2]

Reason: improve performance

# 👎 non-compliant
factorial = lambda n : n * factorial(n-1) if n else 1

# 👍 preference
@cache
factorial = lambda n : n * factorial(n-1) if n else 1

String

  • Reverse string using extended slices syntax
print("xyz"[::-1]) #zyx

Collection

  • Extended slices syntax

To extract elements: range(10)[::2] #[0, 2, 4, 6, 8]
To reverse: range(10)[::-1] #[9, 8, 7, 6, 5, 4, 3, 2, 1, 0]

  • Use list comprehension to generate lists processed (w/ conditions or computations) from raw list:
# 👎 non-compliant
odd_square = [] 
for x in range(1, 11): 
    if x % 2 == 1: 
        odd_square.append(x**2)
        
# 👍 preference
odd_square = [x ** 2 for x in range(1, 11) if x % 2 == 1]
  • Use unpacking generalizations to merge dictionaties, overwrite duplicate [Python3.5]
# 👉 given
x = {'a': 1, 'b': 2}
y = {'b': 3, 'c': 4}

# 👍 preference
print({**x, **y}) #{'a': 1, 'b': 3, c': 4}

OOP

  • Use @dataclass decorator from dataclasses library to generate common function implementations for classes such as __init__, __repr__, __eq__ [Python3.7]

  • Use class/dict/tuple => namedtuple for DTO [Reference]

✔️ Pros: lightweight, short syntax, immutable by defaut, can access properties via index or .