在Ruby中,有没有一种方法可以"重写"子类中的常量,从而从该子类调用继承的方法,导致该方法使用新常量而不是旧常量?例如:
class SuperClass
CONST = "Hello, world!"
def self.say_hello
CONST
end
end
class SubClass < SuperClass
override_const :CONST, "Hello, Bob!"
end
SuperClass.say_hello # => "Hello, world!"
SubClass.say_hello # => "Hello, Bob!"
如果没有,有没有办法改成这样?
class SuperClass
CONST = "Hello, world!"
def self.say_hello
CONST
end
end
SubClass = SuperClass.clone
SubClass.send(:remove_const, :CONST)
SubClass.const_set(:CONST, "Hello, Bob!")
SubClass.say_hello # => "Hello, Bob!"
注意:我在irb中try 了我的第二个示例,它似乎有效,只是在我克隆类之后,类方法似乎无法访问CONST:
irb(main):012:0> SubClass.say_hello
NameError: uninitialized constant Class::CONST
from (irb):4:in `say_hello'
from (irb):12
from C:/Ruby193/bin/irb:12:in `<main>'