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Comment on Python Performance: Why 'if not list' is 2x Faster Than Using len()

JustAnotherKay@lemmy.world ⁨6⁩ ⁨months⁩ ago

Doesn’t matter what it implies. The entire purpose of programming is to make it so a human doesn’t have to go do something manually.

not x tells me I need to go manually check what type x is in Python.

len(x) == 0 tells me that it’s being type-checked automatically

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sugar_in_your_tea@sh.itjust.works ⁨6⁩ ⁨months⁩ ago
That’s just not true:

not x - has an empty value (None, False, [], {}, etc)

len(x) == 0 - has a length (list, dict, tuple, etc, or even a custom type implementing __len__)

You can probably assume it’s iterable, but that’s about it.

But why assume? You can easily just document the type with a type-hint:

def do_work(foo: list | None): if not foo: return ...
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