validates_format_of :email throws error

Validates_format_of :email example available on api.rubyonrails.org is throwing errors.

class Person < ActiveRecord::Base
validates_format_of :email, :with => %r\A([^@\s]+)@((?:[-a-z0-9]+.)+[a-z]{2,})\Z/, :on => :create
end

validates :email, :format => { :with => %r\A([^@\s]+)@((?:[-a-z0-9]+.)+[a-z]{2,})\Z/, :on => :create }

Currently i am using rails 3.2.8 versions.

On loading getting the error as “syntax error, unexpected ‘]’, expecting keyword_end”

%r\A([^@\s]+)@((?:[-a-z0-9]+.)+[a-z]{2,})\Z/
%r\A\Z/
%r/

Maybe use %r!! instead of %r/?