swap-with-temporary-variable (PLR1712)

Preview (since 0.15.3) · Related issues · View source

Derived from the Pylint linter.

Fix is sometimes available.

This rule is unstable and in preview. The --preview flag is required for use.

What it does

Checks for code that swaps two variables using a temporary variable.

Why is this bad?

Variables can be swapped by using tuple unpacking instead of using a temporary variable. That also makes the intention of the swapping logic more clear.

Example

def function(x, y):
    if x > y:
        temp = x
        x = y
        y = temp
    assert x <= y

Use instead:

def function(x, y):
    if x > y:
        x, y = y, x
    assert x <= y

Fix safety

The rule's fix is marked as safe, unless the replacement range contains comments that would be removed.