this post was submitted on 24 Apr 2025
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Python Performance: Why 'if not list' is 2x Faster Than Using len() (blog.codingconfessions.com)
submitted 22 hours ago by jnovinger to c/python
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[โ€“] [email protected] 3 points 7 hours ago (1 children)

foo = "potatoes!"

len(foo)

will give you the number of characters in the string. It's not a surefire way to find a list at all!

[โ€“] [email protected] 2 points 3 hours ago

Same with dictionaries, iterators (will consume the iterator!), and anything else that has a length.

I've actually had the string instead of list issue a number of times, because sometimes things get off and it's hard to track down where things went wrong.

For this reason, I think type hints are the way to go. Use them consistently w/ a static analysis tool like pyright and you'll catch a lot of these issues before running into cryptic error messages.