this post was submitted on 17 Apr 2025
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Why does not without a parameter return True? I'm starting to like the fact that I haven't touched python in a while.
I think it's because
not()is equivalent tonot(None), and sinceNoneis falsynot(None)returnsTrue.Are you sure?
I can't test it now, but to me it looks like
()is an empty tuple. Python behavior is that for logic operations empty set equals to false. Then we applynotto getTrue. Not having space betweennotoperator and parentheses makes it look like it is a function.I'm pretty sure you're right; that makes more sense.
Why is literally nothing equivalent to None? Is it because None is the default value of an optional parameter? (If so why oh why is it optional)
Because nothing isn't something, and something is true. It's base Boolean logic where everything is either true or false. Null/nothing is false.
It's a weird way to think about conditionals, but it makes sense when you use them in real examples. In my case, I use them like this when I need to make sure that a variable has a value. So I can do something like
If(variable){do things with the variable}else{do stuff when the variable doesn't exist}
I understand that, it makes sense. But why does it not throw an error? The parameter is missing after all.
Actually the explanation is wrong.
is actually
notis a keyword not a function.Boolean of empty tuple is
Falseand thennotnegates it.I explained it better here:
https://lemm.ee/post/61594443/19783421
That makes a lot more sense, thanks I did see in the syntax highlighting that it was a keyword but forgot that none of them took parameters.
No it's not, "" (a null/empty string) is the parameter. Not every function needs a parameter to be valid, and negation is one of them. Negating nothing is something, so "not()" = "not(null)" = "not(false)" = "true"
God I love python
in J, many other languages, not null is null.
if not a were null then an if that evaluates that would evaluate it as falsy… also if a would evaluate as falsy :/ that’s far weirder behaviour