通过子类覆盖Parent类变量

Question

家长班：

  

account.rb

class Account
    attr_reader :owner, :interest
    attr_accessor :funds

    def initialize(args)
        @funds = args[:funds]
        @owner = args[:owner]
        @interest = 0.01
    end
end

  

saving_account.rb

class SavingAccount < Account
    attr_reader :interest
    def initialize(args)
        @interest = 0.05
        super(args)
    end
end

当我跑步时

saving_acc = SavingAccount.new(funds: 10000, owner: "Jack")
assert_equal(0.05, saving_acc.interest)

我明白了：

  

NoMethodError：未定义的方法interests' for #<SavingAccount:0x007fa711853828> tests/saving_account_test.rb:13:in test_interests'

我做错了什么？

Answer 1

更改作业前调用super的顺序。

class SavingAccount < Account
    attr_reader :interest
    def initialize(args)
        super(args)
        @interest = 0.05
    end
end

顺便说一下，这是导致错误的拼写错误。

assert_equal(0.05, saving_acc.interests)
                                      ^

除此之外，@interest不是类变量，而是实例变量。

Answer 2

删除结尾的＆＃39;

 saving_acc = SavingAccount.new(funds: 10000, owner: "Jack")
 assert_equal(0.05, saving_acc.interest)