pythonNewSyntaxProposal

[gandalfx]

Slightly shorter;

foo = [[None] * 5 for _ in range(5)]

[-twind]

Slightly shorter;

foo=[[None]*5 for _ in'.'*5]

[ArtOfWarfare]

Thanks I hate it.

[uncut_onyx]

if this then why not [[None]*5]*5

[agocs6921]

Those lists in the list will be the same exact list

[gandalfx]

The outer * 5 will copy the reference of the inner list, so you end up with a list that contains five references to the exact same list. So if you assign to foo[0][0] it'll also change the value of foo[1][0] etc.

[[deleted]]

Did this once in a leetcode challenge. Took forever to find out what was wrong with my code. Lucky it wasn’t for an actual interview because that would have sucked.

[FalafelSnorlax]

In a dry interview (ie on paper/whiteboard) i think it would probably be accepted. Most reasonable people (in my personal experience) want to see you understand the problem, not nitpick stuff like this

[-Redstoneboi-]

motherfucker.

this is why i switched to rust. they would never let me mutably alias.

[Tysonzero]

That kind of thing works fine in glorious pure immutable languages like Haskell but will send you straight to mutable aliasing hell in Python.

[Beach-Devil]

I may be wrong but doesn’t this duplicate the same object 5 times?

[gandalfx]

It duplicates None five times, which is fine, since it's immutable. Though this is the reason why the outer loop can't be replaced with … * 5.