[mathisfun123]

> list object is constructed once and assigned to both variables

Ummm no the list is constructed once and assigned to b and then b is assigned to a. It would be crazy semantics if `a = b = ...` meant `a` was assigned `...`.

Edit: I'm wrong it's left to right not right to left, which makes the complaint in the article even dumber.

[kccqzy]

It’s assigned left to right, not right to left. It’s documented in the Python language reference.

> An assignment statement evaluates the expression list and assigns the single resulting object to each of the target lists, from left to right.

Consider this:

    a = [1, 2]
    i = a[i] = 1

If assignment were to happen right to left, you would get a NameError exception because the first assignment would require an unbound variable.

[mathisfun123]

Fine but that even moreso illustrates how goofy the expectation that the "ctor" for [] would be called twice.

[ayhanfuat]

> then b is assigned to a

Wouldn't that require a LOAD_FAST? Also a is assigned first (from left to right) so a = ... happens either way.