ruby: workarounds for nested string interpolation

Question

In the string
"#{x ? (x.to_s + ' is ') : ''}ok", Rubocop's Style/StringConcatenation suggests avoiding the +.
But that requires a nested string interpolation
"#{x ? '#{x.to_s} is ' : ''}ok)",
which at least in Ruby 2.7 is not expanded: #{x.to_s} is treated like any other literal.

Is the + version alright because it's on the fringes of what a style guide could cover, or must one introduce a temporary variable?

tmp = x ? '#{x.to_s}  is '  : ''
"#{tmp}ok"

---

Context: the string is sent to a logfile. ok is actually a long list of details. x is worth logging, but only when it exists.

question from:https://stackoverflow.com/questions/65850119/ruby-workarounds-for-nested-string-interpolation

Answer 1

Yes, a variable will make this more readable (imo):

prefix = "#{x} is " if x
"#{prefix}ok"

(this relies on the fact that nil#to_s == '')