Unnecessary else Statement Can Be Better for Readability

Just watched a short video by Trey Hunner and thought it was a good rule.

Balanced Statements

If the else statement is not more important than the if check, then keeping it can improve readability. The if and the else statements are like a balance scale.

Example

from dateutil.parser import parse

def earliest_data(date1, date2):
    """Return the string representing the earliest date."""
    if parse(date1, fuzzy=True) < parse(date2, fuzzy=True):
        return date1
    else:
        return date2

Unnecessary and Confusing else Statement

However, if the else statement is more important than the if check, it is better to remove the else statement.

Example

from pathlib import Path

def calculate_directory_size(path):
    path = Path(path)

    if path.is_file():
        return path.stat().st_size

    return sum(
        calculate_directory_size(item)
        for item in path.iterdir()
    )