csv - Ruby: Why don't we need `attr_accessor`? -

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i ran through example 1.9 pickaxe book , i'm confused why following program runs without using attr_accessor in csv_reader.rb file.

book_in_stock.rb

class bookinstock   attr_accessor :price, :isbn    def initialize(price, isbn)     @price = float(price)     @isbn = isbn   end end

aren't writing instance variable of csv_reader object appending new bookinstock objects it?

csv_reader.rb

require 'csv' require_relative 'book_in_stock'  class csvreader   def initialize     @book_in_stock = []   end    def read_in_csv_data(csv_file)     csv.foreach(csv_file, headers: true) |row|       @book_in_stock << bookinstock.new(row["price"], row["isbn"])     end   end    def total_value_in_stock     sum = 0     @book_in_stock.each {|book| sum += book.price}     sum   end end

test_data.csv

"price","isbn" "44.12",'asdf34r13' "74.12",'asdf34r13' "14.12",'asdf34r13' "42.12",'asdf34r13' "4774.12",'asdf34r13' "04.19",'asdf34r13'

program driver

require_relative 'csv_reader'  reader = csvreader.new  argv.each |csv_file_name|   stderr.puts "processing thing"   reader.read_in_csv_data(csv_file_name) end  puts "total value = #{reader.total_value_in_stock}"

is read_in_csv_data method doing same job accessor method?

attr_accessor creates 2 methods if write them hand:

def price   @price end  def price=(new_price)   @price = new_price end

you never calling of methods, irrelevant whether exist or not.


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