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How to Style Multiline If Statements in Python

Writing clear and readable code is crucial for maintainability.

This guide explores best practices for formatting multiline if statements in Python, aligning with the recommendations of the PEP 8 style guide. We'll cover using parentheses for line continuation and proper indentation to enhance code readability.

Multiline if Statements with Parentheses​

The preferred way to format multiline if statements according to PEP 8 is to use parentheses to break up long conditions. This leverages Python's implied line continuation within parentheses, brackets, and braces.

Using Extra Indentation​

You can use additional indentation to distinguish between the conditions in the if statement and the code block.

if ('hi' == 'hi' and
        len('hi') == 2 and
        2 == 2):
    print('success')
  • Parentheses are used to wrap the entire conditional expression.
  • The code block is indented at the normal level.
  • Additional indenting is used for the continuation of the conditions, which helps with differentiating the conditional expressions from the if block.

Putting Each Condition on a New Line​

You can also put each condition on a new line to improve readability further. This is the recommended approach for longer and more complex if statements.

if (
    'hi' == 'hi' and
    len('hi') == 2 and
    2 == 2
):
    print('success')
  • The parentheses are used for line continuation.
  • All conditions are on separate lines, and do not need additional indentation as the closing parenthesis will signal the end of the conditions.
  • This approach eliminates the need for extra indentation in the condition lines and separates each condition clearly.

While using backslashes for line continuation is still valid, it is not recommended by PEP 8, and it is better to avoid this method and instead use parentheses. However, it's useful to be aware of this syntax.

if 'hi' == 'hi' and \
        len('hi') == 2 and \
        2 == 2:
    print('success')
  • Backslashes are used for line continuation.
  • When using backslashes, it's important to indent the continued lines to avoid confusion with the code block.

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