You can override Ruby’s method_missing method to make dynamic methods based on regex.
For example, a trivial case, User can have three string gender settings: "male", "female" and "other" and you want checker methods of the style gender_male? gender_female? gender_other?.
It is not DRY to write these three repetetive methods. Use method_missing!
Follow this pattern using case, that way you can add several when clauses to provide different regex-matched dynamic methods (make sure they do not overlap!)

def method_missing(method_sym, *arguments, &block)
  # the first argument is a Symbol, so you need to_s it if you want to pattern match
  case method_sym.to_s
  when /gender_(.*)\?/
    return $1 == gender
  else
    super
  end

end

def respond_to?(method_sym, include_private = false)
  case method_sym.to_s
  when /gender_(.*)\?/
    true
  else
    super
  end
end

Reference