創建從一個類的對象這是繼承紅寶石

Question

林就如何落實這個掙扎的理解（谷歌搜索後）：我有一個類：

class Student 
    # constructor method 
    def initialize(name,age) 
     @name, @age = name, age 
    end 

    # accessor methods 
    def getName 
     @name 
    end 
    def getAge 
     @age 
    end 

    # setter methods 
    def setName=(value) 
     @name = value 
    end 
    def setAge=(value) 
     @age = value 
    end 
end 

而且可以說我有另一個類，從學生繼承

class Grade < Student 
    #constructor method 
    def initialize(grade) 
     super 
     @grade = grade 
    end 

    # accessor methods 
    def getGrade 
     @grade 
    end 

    # setter methods 
    def setGrade=(value) 
     @grade = value 
    end 
end 

我知道如何建立一個下賤：

student = Student.new(name, age) 

如何建立這個Student（我剛纔創建）與學生相關的Grade對象，我怎麼會叫繼承的對象，比如我想：

puts 'student name and associated grade'

我知道我可以把Student內的等級變量類，但爲了學習即時通訊這樣做的目的。

Answer 1

首先，沒有必要在Ruby中定義存取這樣的，它遠遠習慣。讓我們先清理一下：

class Student 
    attr_accessor :name, :age 

    def initialize(name, age) 
    @name =name 
    @age = age 
    end 
end 

class Grade 
    attr_accessor :value 

    def initialize(grade) 
    @value = grade 
    end 
end 

其次，它似乎並不像Grade應該從Student繼承所有，只是調整後者還存儲Grade實例變量：

class Student 
    attr_accessor :name, :age, :grade 

    def initialize(name, age, grade = nil) 
    @name =name 
    @age = age 
    @grade = grade 
    end 
end 

然後，您可以實例化一個這樣的學生：

student = Student.new("Test", 18, Grade.new(1)) 

或者因爲默認值，你離開等級並分配它er：

student = Student.new("Test", 18) 
# later 
student.grade = Grade.new(1) 

Answer 2

該代碼會做你想要的東西：

class Grade 
    attr_accessor :value 
    def initialize value 
    @value = value 
    end 
end 

class Student 
    attr_accessor :name, :age, :grade 
    def initialize name, age, grade 
     @name, @age, @grade = name, age, Grade.new(grade) 
    end 
end 

st = Student.new 'John', 18, 5 
puts "student #{st.name} and associated grade #{st.grade.value}"