You have no clue what type of data ends up in `items`, or that something should end up in `items` at all. This is obvious.
items =
You have no clue what type of data ends up in `items`. You just know now, that something will end up there.
items = [
You only know that a list will be in `items`. Not what will be in the list.
items = [ this
You only know that a list will be in `items`. Not what will be in the list. You have no clue what is `this`.
items = [ this for
You only know that a list will be in `items`. Not what will be in the list. You have no clue what is `this`.
items = [ this for iterator
You only know that a list will be in `items`. Not what will be in the list. You have no clue what is `this`. You cannot have, or you break the right to left propagation with nested cases, against what you have with this simple example of yours.
items = [ this for iterator ]
This is the only time when you know what type is `items` or `this`.
Also `this` is a useless identifier, if you cannot transform or filter in your list comprehension. I don't like mine either that it contains pointless words...
Don't get me wrong, your example is clearly a right to left data flow. Which is not inherently bad, because `items` and `this` are new identifiers, which won't figure out by IDEs, so it doesn't matter.
Also, in my example of Python code (not my version of it, but the valid Python code), there is no need to have `if` at all to break intellisense, or break either left to right or right to left data flow several times inside the list comprehension.
If you named your variables properly and your editor supported type hints, you'd have none of these issues: I used generic names for demonstration.
Compare it to
family_adults = [ person for person in family_members if person.age >= 18 ]
Code should be as readable as possible by default: I'd argue you do not even need types in code with good naming, though they do prove their worth in codebases being evolved for a long time and many people.
Again the bigger problem is the 'if', including in comprehensions.