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Ruby Ruby Objects and Classes Build a Bank Account Class Printing The BankAccount

Posted by David Greenstein
David Greenstein
6,734 Points

Why are we able to do interpolation with balance here?

Why are we able to do interpolation with balance when its not an instance variable like name

def to_s
    "Name: #{name},Balance: #{balance}"
  end
bank_account.rb 
class BankAccount
  attr_reader :name

  def initialize(name)
    @name = name
    @transactions = []
    add_transaction("Beginning Balance", 0)
  end

  def balance
    balance = 0
    @transactions.each do |transaction|
      balance += transaction[:amount]
    end
    balance
  end

  def debit(description, amount)
    add_transaction(description, -amount)
  end

  def credit(description, amount)
    add_transaction(description, amount)
  end

  def add_transaction(description, amount)
    @transactions.push(description: description, amount: amount)
  end

  def to_s
    "Name: #{name},Balance: #{balance}"
  end

end

1 Answer

Maciej Czuchnowski
Maciej Czuchnowski
36,441 Points
Maciej Czuchnowski
Maciej Czuchnowski
36,441 Points

It's still a method, so whatever that method returns, will be interpolated. Notice that instance variable @name by itself would have to be interpolated as #{@name} in normal circumstances, but attr_reader :name creates a method called name, which simply returns the value of the instance variable @name. So in both cases - name and balance - you're interpolating method return values.