Classes, Objects, and Variables(Chapter 3 of Programming Ruby)

csv_reader.rb

1 require 'csv'

2 require_relative 'book_in_stock'

3 class CsvReader

4 def initialize

5 @books_in_stock = []

6 end

7 def read_in_csv_data(csv_file_name)

8 CSV.foreach(csv_file_name, headers: true) do |row|

9 @books_in_stock << BookInStock.new(row["ISBN"], row["Amount"])

end

end

def total_value_in_stock

sum = 0.0

@books_in_stock.each {|book| sum += book.price}

sum

end

def number_of_each_isbn

# ...

end

end

stock_stats.rb

require_relative 'csv_reader'

reader = CsvReader.new

ARGV.each do |csv_file_name|

STDERR.puts "Processing #{csv_file_name}"

reader.read_in_csv_data(csv_file_name)

end

puts "Total value = #{reader.total_value_in_stock}"

ruby stock_stats.rb test.csv

Processing test.csv
Total value = 122.07