So far, this chapter has shown you how to use a number of the helper methods that come with Rails. You can also create your own helper methods. There are lots of good reasons to do so:
You can come closer to Rails’ DRY (Don’t Repeat Yourself) ideal if you can combine multiple pieces into a single invocation.
You can see more obviously which pieces of your code are actually doing the same work when they call the same method, instead of perpetually reinventing the wheel.
The same code used in multiple places will rarely stay identical.
Multiple views within an application can reference the same helper methods.
Creating helper methods might not be your very first priority in creating an application, but once you have a basic idea of what you want to create in your views, it’s a good idea to start assembling common tasks into helper methods.
Within the application directory structure, helper methods go into
the app/helpers directory. At this point, the guestbook application will
have two files there: application_helper.rb and people_helper.rb.
Helper methods that are defined in application_helper.rb are available to
views throughout the entire Rails application, whereas methods defined
in people_helper.rb are only
available to views that pertain to operations on the
person model. For now,
the helper methods built in this section can go in people_helper.rb and graduate to application_helper.rb if you ...