Regex is just a prominent example of a certain pattern. Depending on work and style, one often has functions which return something, on which in case of a non-empty result you want to do something more. Walrus can shrink the code in data-intensive code quite well from my experience.

I've come to like using:

    if foo := data.get("foo"):
        handle_foo(foo)

That’s exactly the same as this, though.

    foo = data.get("foo")
    if foo:
        handle_foo(foo)

The only place I have found the walrus operator useful is in similar `while` loops, where the equivalent code would be:

    while True:
        foo = data.get("foo")
        if not foo: break
        handle_foo(foo)

The loop can be written using This One Weird Trick that Walruses Hate:

  for foo in iter(partial(data.get, "foo"), None):
      handle_foo(foo)

So I would only use the walrus operator for the first example (the if statement), which even though it is exactly the same as doing it in two steps just feels nicer as a single step.

No it's not the same. The visibility of variable "foo" is extended beyond it's usefullness if you use `if`.

No, the visibility of `foo` is the same in both examples. Python’s `if` statements do not introduce a new scope.