Python Best Practices: Helper functions over complex expressions
Python powerfull syntaxis and List Comprehensions allows creating one-lined expressions that can do many things at once.
This is not always good, in Python, we favor readability instead of obscure bodoo. Remember:
Code gets read many more times that is written
Take this example as consideration
matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] filtered = [[x for x in row if x % 3 == 0] for row in matrix if sum(row) >= 10] print(filtered)
Excerpt From Brett Slatkin. “Effective Python: 59 Specific Ways to Write Better Python (Effective Software Development Series).” Apple Books.
What does it do? Not easy to tell.
Take this other code, that does exactly the same thing:
matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] filtered = filter_sum_more_than(matrix, 10) divisible_by_3 = get_divisable_by(filtered, 3) print(divisible_by_3)
Powerful expressions are cool to show off a little bit with other programmers, but increase unnecessarily the readability of the code.
a = [...] ven_squares = map(lambda x: x**2, filter(lambda x: x % 2 == 0, a))
Can you guess quickly what this does?
Can you find a better way to write this?
Explicit is better than implicit
[The Zen of Python] (https://www.python.org/dev/peps/pep-0020/)
Split into different functions if:
- Your List Comprehensions expressions have more than 2 operations
- If your functions are solving more than one problem
- If your functions do not fit your screen
- If some part of the code can be potentially reused
- If you see code that you have already written someplace else