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Ruby Ruby Objects and Classes Variables and Methods Instance Variables and Local Variables

Posted by Vamsi Pavan Mahesh Gunturu
Vamsi Pavan Mahesh Gunturu
4,541 Points

unable to use methods inside methods

class MyName
  def initialize(title, firstName, middleName, lastName)

    @title = title
    @first = firstName
    @middle = middleName
    @last = lastName

   end

  def title
    puts @title
  end

  def first
    puts @first
  end

 def middle
   puts @middle
 end

 def last
   puts @last
 end  

 def full
   title() + first()
  end
end

name = MyName.new("mr","vamsi","pavan","mahesh")
name.title 
name.first
name.middle
name.last
name.full  

This gives me 
myclass.rb:28:in `full': undefined method `+' for nil:NilClass (NoMethodError)                                              
        from myclass.rb:37:in `<main>'

3 Answers

Roberto Alicata
PLUS
Roberto Alicata
Courses Plus Student 39,959 Points
Roberto Alicata
Roberto Alicata
Courses Plus Student 39,959 Points

delete the "puts" statements in the functions and it will works

Vamsi Pavan Mahesh Gunturu
Vamsi Pavan Mahesh Gunturu
4,541 Points

Thanks!

Tim Knight
Tim Knight
28,888 Points
Tim Knight
Tim Knight
28,888 Points

Vamsi, Ruby actually makes this a lot easier on you by just creating reader accessors. Additionally it's more idiomatic in Ruby to use snake-case over camel case, so another way to rewrite this whole block would be:

class MyName
    attr_reader :title, :first_name, :middle_name, :last_name

    def initialize(title, first_name, middle_name, last_name)
       @title = title
       @first_name = first_name
       @middle_name = middle_name
       @last_name = last_name
    end

    def full_name
       "#{title} #{first_name} #{middle_name} #{last_name}" 
    end
end

name = MyName.new("mr","vamsi","pavan","mahesh")

puts name.title        # => mr
puts name.first_name   # => vamsi
puts name.middle_name  # => pavan
puts name.last_name    # => mahesh
puts name.full_name    # => mr vamsi pavan mahesh
Chris Ward
Chris Ward
12,129 Points
Chris Ward
Chris Ward
12,129 Points

Is puts returning nil?

Try this code instead in your custom defined getters:

retVal = puts @instanceVarName
retVal = (retVal.is_nil?) ? @instanceVarName.to_s : retVal.to_s

DONT FORGET TO REPLACE @instanceVarName WITH THE NAME OF THE INSTANCE VAR!

Tim Knight
Tim Knight
28,888 Points
Tim Knight
Tim Knight
28,888 Points

Remember that a method returns an output, it doesn't "put" an output... if you run puts by itself you'll see it returns nil. If you puts with string you'll get the string and then nil back. So as far as I can see it, if you us puts as the last thing in a method it's going to return the last thing in the method (which Ruby does by default), which is in fact nil.

2.2.1 :001 > @name = "Tim"
 => "Tim"
2.2.1 :002 > @name
 => "Tim"
2.2.1 :003 > def name
2.2.1 :004?>   puts @name
2.2.1 :005?> end
 => :name
2.2.1 :006 > name
Tim
 => nil
2.2.1 :007 > def name
2.2.1 :008?>   @name
2.2.1 :009?> end
 => :name
2.2.1 :010 > name
 => "Tim"
2.2.1 :011 >