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Comment by frogcoder | Hacker News Reader

Funny, I think the walrus operator makes code cleaner and easier to understand.

Many of my code were like this:

    foo = one_or_none()
    if foo:
        do_stuff(foo)

Now I have the following:

    if foo := one_or_none():
        do_stuff(foo)

This kind of code happens quite frequently, looks nicer with walrus operator to me.

I haven't yet fully adjusted to the walrus operator, but to me the choice would depend on what happens _after_ the "if" statement.

In both cases, "foo" continues to exist after the "if" even though the second example makes it look like "foo" is scoped to the "if".

So to my eye, the following would look super weird (assume do_more_stuff can take None):

    if foo := one_or_none():
        do_stuff(foo)
    do_more_stuff(foo)

whereas the following would look fine:

    foo = one_or_none()
    if foo:
        do_stuff(foo)
    do_more_stuff(foo)

Honestly, for this specific case, I prefer one_or_none() to return an iterable with zero or one items, and then just doing:

  for foo in one_or_none():
    do_stuff(foo)

If you don't control one_or_none, but it returns an Optional, you can wrap it with something like:

  def optional_to_tuple(opt_val: Optional[T]) -> Tuple[]|Tuple[T]:
    return (opt_val,) if opt_val is not None else ()

Would have been more Pythonic as:

    if one_or_none() as foo:
        do_stuff(foo)

I didn't recognize this use of "as" as valid Python, but tried it in 3.9 just to be sure. Got a syntax error (as expected).

I am not fully up to speed with 3.10, but quickly checked the docs and it doesn't appear to have been added in 3.10 either.

Let me know if I'm missing something.

Oh, "would have" meaning python-dev chose a different spelling. Not, as in it would-have been better if the example was written this way.

Oh, I see now. Thanks for the clarification.