How to show the result of the show method in Ruby [closed]

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How to show the result of the show method in Ruby [closed]

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#2 by (0 votes)

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I have a problem calling the show method, this should show the list of items in the shopping cart, but I get an empty string as a result.

class ShoppingCart

  def initialize
    @items = {:apple => 10, :oranges => 5 , :grapes => 15, :banana => 20, :watermelon => 50}
    @cost_total = 0
  end

  def add_item_to_cart(item)
    @cost_total += @items[item]
  end

  def show
    puts "#{@items[].each}"
  end

  def cost
    puts "#{@cost_total}"
  end

end

=begin
class Discounts
  def discounts_apple(item)
    if item(:apple) == 2
    end

  end
  =end

  cart = ShoppingCart.new

  cart.add_item_to_cart(:apple)
  cart.add_item_to_cart(:banana)
  cart.add_item_to_cart(:banana)

  #cart.show
  #1 apple: 10$
  #2 bananas: 40$
  cart.show
  cart.cost

ruby

asked by Marcos Collado 09.06.2016 в 18:41

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2 answers

Error 'source not found' when I'm going to perform debug in Eclipse Error with the Vegas plugin

score 0 · Answer 1

The show method is calling the method each which initiates an iteration but does not indicate what to do with the information in this case show it, to get the list as indicated in the comments you should change it for this:

def show
  @items.map{|key, value| puts "#{key}" : "#{value}"}
end

score 0 · Answer 2

To be able to show the number of items added to the cart you must have proof of all those that you have added. That is why I advise you to use a new variable to save them:

def initialize
  @items = {:apple => 10, :oranges => 5 , :grapes => 15, :banana => 20, :watermelon => 50}
  @cart = Hash.new(0)
  @cost_total = 0
end

@cart is a hash whose new keys have a default value of 0 . In this way, in add_item_to_cart you can add an item to the cart if it does not exist, but if it exists, increase the amount by one:

def add_item_to_cart(item)
  @cart[item] += 1
  @cost_total += @items[item]
end

To show the cart you can do something like this:

def show
  @cart.each do |item, cantidad|
    puts "#{cantidad} #{item}: #{cantidad * @items[item]}$"
  end
end

The shopping cart is traversed, to show each item, along with its quantity and price (number of items * item value). When executing this:

cart = ShoppingCart.new
cart.add_item_to_cart(:apple)
cart.add_item_to_cart(:banana)
cart.add_item_to_cart(:banana)
cart.show

We get:

1 apple: 10$
2 banana: 40$

PD: As an extra, a more "rubista" way to calculate the total cost, would be to use a method that returns the price instead of using a variable. What is the advantage? Well, if in the future you want to add a new method that would allow the customer to remove an item from the cart, it would be much easier to update the correct price:

def cost
  @cart.inject(0) { |sum, (k,v)| sum + v * @items[k] }
end

At first glance, it seems a very strange method, does not it? inject allows you to perform arithmetic operations with the data. In this case, the objective is to add the price of all the items. sum is initially worth 0 , and it is added to the number of items in the cart multiplied by its value, where k and v are the key and the value of @cart .