Undefined local variable or method 'name'

Question

Below is a program that implements a tree.

class Tree
    attr_accessor :children, :node_name

    def initialize(name_children=[])
        @children = children
        @node_name = name
    end

    def visit_all(&block)
        visit &block
        children.each {|c| c.visit_all &block}
    end

    def visit(&block)
        block.call self
    end
end

ruby_tree = Tree.new( "Ruby", [Tree.new("Reia"), Tree.new("MacRuby")] )

puts "Visiting a node"
ruby_tree.visit {|node| puts node.node_name}
puts 

puts "visiting entire tree"
ruby_tree.visit_all {|node| puts node.node_name}

When I run this code it errors at this line

ruby_tree = Tree.new( "Ruby", [Tree.new("Reia"), Tree.new("MacRuby")] )

The error I'm receiving is

tree.rb:6:in `initialize': undefined local variable or method `name' for #<Tree:0x007f94020249f8 @children=nil> (NameError)
from tree.rb:19:in `new'
from tree.rb:19:in `<main>'

Any help would be awesome.

In your constructor, (initialize), why aren't you entering the variables children, and name as such instead of a children_name ? What it seems to me is that when you are trying to instantiate the class by creating the objects, when it goes to the initialize constructor, it does not find a name in there. — patricio
– patricio, Commented Oct 11, 2015 at 16:23

Idan Arye · Accepted Answer · 2015-10-11 16:21:55Z

3

You have a typo in your initialize method accepts a single argument named name_children, but from the body of that method it looks like the underscore should have been a comma - name, children.

answered Oct 11, 2015 at 16:21

Idan Arye

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grimsock · Accepted Answer · 2015-10-11 16:21:24Z

1

Here's the problem - line 6 @node_name = name. Where do you define that variable?

answered Oct 11, 2015 at 16:21

grimsock

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Comments

patricio · Accepted Answer · 2015-10-11 16:27:23Z

0

In your constructor, (initialize), why aren't you entering the variables children, and name as such instead of a children_name ? What it seems to me is that when you are trying to instantiate the class by creating the objects, when it goes to the initialize constructor, it does not find a name in there.

def initialize(name, children=[])
    @children = children
    @node_name = name
en

answered Oct 11, 2015 at 16:27

patricio

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1 Comment

user3834435 Over a year ago

Thanks for help guys, I fixed up the typo.

Arvind Kumar · Accepted Answer · 2015-10-12 14:06:09Z

0

As you have define attr_accessor :name in your Model so there you have to define Children method in you model like as

def self.name
    # here will be you code which you want 
 end

answered Oct 12, 2015 at 14:06

Arvind Kumar

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