What does #{…} mean?

Question

Such as in the following code from Why\'s Poignant Guide:

def wipe_mutterings_from( sentence ) 
     unless sentence.respond_to? :include?
         raise Arg         


        

Answer 1

#{} is used for Ruby interpolation. In this example,

this will raise an ArgumentError with the message,

cannot wipe mutterings from a

This is a useful read - String concatenation vs. interpolation in Ruby