"Nested" ternary in string interpolation ambiguity

[sparr]

a ? "x #{ b ? 'y' : 'z' }" : ''

Is this a nested ternary, of the sort that https://rubystyle.guide/#no-nested-ternary prohibits?

If not, could that be made explicit in some way?

[koic]

This is not a case where a ternary operator is directly used inside another ternary operator. What's inside the ternary operator is just an interpolated string, and the ternary operator appears only within the string interpolation.It doesn't seem appropriate to treat this the same as a nested ternary. I’m not sure it would be reasonable to prohibit this by rule.

[sparr]

The reason I ask is that rubocop currently thinks that this violates that rule.

[koic]

I see. Looking at the test cases for the relevant cop, I found that it indeed detects cases like the following:

cond ? foo : bar(foo.a ? foo.b : foo) { |e, k| e.nil? ? nil : e[k] } 

For consistency with the current behavior of the cop, the example in question would also count as a nested ternary.

[pirj]

It feels that it does not only violate the rule, it is one level worse in terms of readability.

[sparr]

I think it was actually more readable with string concatenation, before applying the string formatting cop.