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unnecessary-double-cast-or-process (C414)

Added in v0.0.70 · Related issues · View source

Derived from the flake8-comprehensions linter.

Fix is always available.

What it does

Checks for unnecessary list(), reversed(), set(), sorted(), and tuple() call within list(), set(), sorted(), and tuple() calls.

Why is this bad?

It's unnecessary to double-cast or double-process iterables by wrapping the listed functions within an additional list(), set(), sorted(), or tuple() call. Doing so is redundant and can be confusing for readers.

Example

list(tuple(iterable))

Use instead:

list(iterable)

This rule applies to a variety of functions, including list(), reversed(), set(), sorted(), and tuple(). For example:

  • Instead of list(list(iterable)), use list(iterable).
  • Instead of list(tuple(iterable)), use list(iterable).
  • Instead of tuple(list(iterable)), use tuple(iterable).
  • Instead of tuple(tuple(iterable)), use tuple(iterable).
  • Instead of set(set(iterable)), use set(iterable).
  • Instead of set(list(iterable)), use set(iterable).
  • Instead of set(tuple(iterable)), use set(iterable).
  • Instead of set(sorted(iterable)), use set(iterable).
  • Instead of set(reversed(iterable)), use set(iterable).
  • Instead of sorted(list(iterable)), use sorted(iterable).
  • Instead of sorted(tuple(iterable)), use sorted(iterable).
  • Instead of sorted(sorted(iterable)), use sorted(iterable).
  • Instead of sorted(reversed(iterable)), use sorted(iterable).

Fix safety

This rule's fix is marked as unsafe, as it may occasionally drop comments when rewriting the call. In most cases, though, comments will be preserved.