超類未初始化的常量

Question

我在Foo和Foo2類中有FUU constante，爲了幹我的代碼，我在BaseStuff超類中移動了一個方法。就像這樣：

class BaseStuff 
    def to_s 
    FUU 
    end 
end 

class Foo < BaseStuff 
    FUU = "ok" 
end 

class Foo2 < BaseStuff 
    FUU = "ok2" 
end 

但我的問題是，後：

a = Foo.new 
puts a.to_s 

我得到這個錯誤：

NameError: uninitialized constant BaseStuff::FUU

是否有解決這一問題的最佳做法？

Answer 1

class BaseStuff 
    FUU = nil 
    def to_s 
    self.class::FUU 
    end 
end 

class Foo < BaseStuff 
    FUU = "ok" 
end 

class Foo2 < BaseStuff 
    FUU = "ok2" 
end 

a = Foo.new 
puts a.to_s # => ok 

puts Foo2.new.to_s # => ok2 

Answer 2

class Foo < BaseStuff 
    ::FUU = "ok" 
end