Wrapping a string in this class gives you a prettier way to test for equality. The value returned by Rails.env is wrapped in a StringInquirer object so instead of calling this:

Rails.env == "production"

you can call this:

Rails.env.production?
Methods
M
Instance Public methods
method_missing(method_name, *arguments)

Source: show | on GitHub 

# File activesupport/lib/active_support/string_inquirer.rb, line 13
def method_missing(method_name, *arguments)
  if method_name.to_s[-1,1] == "?"
    self == method_name.to_s[0..-2]
  else
    super
  end
end