在Python中访问列表初始化内的元素

Question

In Python 3 is it possible to access a list element inside this list initialization? I think, it's impossible, but I'm interested just in case it is.

For example, something like this:

lst = [0, 1, 2, 3] + lst[0]

or

lst = [0, 1, 2, 3, lst[0]]

Thank you in advance!

Answer 1

No. The entire right-hand side of the assignment is evaluated before it is assigned to the name on the left. So you can't use lst on the right because lst doesn't exist until after the right-hand side has finished evaluating.

Answer 2

You still don't have a name for the part of lst you want to access, so you cannot access it.

But defining a name is trivial:

left_lst = [1, 2, 3]
lst = left_lst + left_lst[2:3]