Ruby: eval with string interpolation

Question

I don\'t understand, why eval works like this:

\"123 #{456.to_s} 789\" # => \"123 456 789\"
eval(\'123 #{456.to_s} 789\') # => 123
         


        

Answer 1

You wanted:

eval('"123 #{456.to_s} 789"')

. . . hopefully you can see why?

The code passed to the interpretter from eval is exactly as if you had written it (into irb, or as part of a .rb file), so if you want an eval to output a string value, the string you evaluate must include the quotes that make the expression inside it a String.