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Comment by EdwardDiego | Hacker News Reader

Using * on a sequence wouldn't get past code review with me, it's an obscure feature with surprising side-effects and it doesn't explain your thinking.

Only context I've ever found it useful in, is if you're unit testing something that accepts a string of max length M, then

    bad_str = "A" * (M + 1)

Is quite nice and also, easy to interpret.

But if you're calling multiply on a list[list[Any]] lol nah mate, what the hell are you playing at, make a for loop and add comments.

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I feel like far too much attention is given to `[[]] * n`. In the grand scheme of things, no serious python programmer is using multiply on a sequence outside of the string construction convenience.

It's also remarkebly easy to diagnose once you see the unexpected behaviour, so anyone asking for help is going to be instantly told not to do it and use a comprehension instead.

I'm sure there are plenty of other pitfalls in other languages, though I concede this one is especially unintuitive to a new person.

> Using * on a sequence wouldn't get past code review

On a mutable sequence. Or anything mutable. [] being a sequence is not the issue here.

If you work with immutable stuff, * is really not an issue.

It's not great though. I do use it to repeat strings but it should have been a method and not weirdly overloading *. This type of misuse of operator overloading is why people from a C++ background think operator overloading is evil. In python it's mostly ok, due to a more restrained culture, but this is a good example of when it's bad.

It's not weirdly overloaded.

'a'*3 == 'a'+'a'+'a'

There's always the `zip(*[iter(x)]*2)` to split an iterable into even/odds.

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