To give instances access to
the instance variables, we need
to define new methods like we do here:
Note that we need to first be able to
access the value to change it.
Now imagine, that the CoffeeMaker has
not one but five instance variables. For this
to work, we'll have to create 5 methods
to provide access to read them and 5 methods
to change their respective values. This can
quickly become difficult to manage.
In Ruby, we can use attr_writer
along with
attr_reader
to give object instances a simpler
way to update the instance variables: