Let’s assume we have a class called Person:
class Personendperson = Person.new person.name #=> NoMethodError: undefined method `name' for #<Person:0x000055659b8bfb68>If we don’t define a method called name, we will get an error like above (NoMethodError). So let’s define our method.
class Person def name @name # instance variable endendperson = Person.newperson.name # => nilperson.name = "Ecmel"... read more
attr_accessor Usage in Ruby
Let’s assume we have a class called Person:
class Person
end
person = Person.new
person.name #=> NoMethodError: undefined method `name' for #<Person:0x000055659b8bfb68>
If we don’t define a method called name, we will get an error like above (NoMethodError). So let’s define our method.
class Person
def name
@name # instance variable
end
end
person = Person.new
person.name # => nil
person.name = "Ecmel" # => NoMethodError: undefined method `name='
We defined the name method, but we can only read it, we cannot assign any value. Let’s define writer method.
class Person
def name # reader
@name
end
def name=(str) # writer
@name = str
end
end
person = Person.new
person.name = "Ecmel"
person.name # => "Ecmel"
Now we can access and change the value of the instance variable (@name) using the reader and writer methods. So will we define these methods this way every time? Nope! We can use attr_reader for reader methods and attr_writer for writer methods.
class Person
attr_reader :name
attr_writer :name
end
We can also use attr_accessor for reading and writing methods instead of defining them separately. Moreover attr_accessor creates instance variable that called @name.
class Person
attr_accessor :name
end
def say_hello
"Hello #{@name}"
end
person = Person.new
person.name = "Ecmel"
person.say_hello # => "Hello Ecmel"
