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unnecessary-generator-list (C400)#

Derived from the flake8-comprehensions linter.

Fix is always available.

What it does#

Checks for unnecessary generators that can be rewritten as list comprehensions (or with list directly).

Why is this bad?#

It is unnecessary to use list around a generator expression, since there are equivalent comprehensions for these types. Using a comprehension is clearer and more idiomatic.

Further, if the comprehension can be removed entirely, as in the case of list(x for x in foo), it's better to use list(foo) directly, since it's even more direct.


list(f(x) for x in foo)
list(x for x in foo)
list((x for x in foo))

Use instead:

[f(x) for x in foo]

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.