[orf]

It doesn’t and shouldn’t have a sort method because python prefers functions that act on objects rather than methods attached to objects.

That’s why you use “len(obj)” rather than “obj.len()”, and why you use “sorted(dict_keys)” rather than adding a “sort” method to random iterables.

[marcosdumay]

Oh, ok. I was comparing it with 'list.sort()', but yeah, this one mutates the list and returns None (just checked it), so 'sorted' is the expected way to sort a dictionary keys, and my post is just wrong.

[orf]

'list.sort()' is one of those leftovers from "Python before it was really Python" and is not one that's particularly worth it to change because it's useful sometimes.

In general Python prefers builtins that operate on protocols. You use "len(x)" because it's consistent, otherwise you might call "x.len()", "x.length", "x.size()" or any other number of possibilities. And if an object doesn't define it? You're out of luck. With this any object that supports the protocol (__len__) can be passed to length.

The same applies to "sorted()". list.sort() is useful in some specific circumstances where "sorted()" is not adequate, but in general the answer to "how do I sort something" is to use sorted.