ruby - Accessing constants outside a class

Question

When I want to access the constant CONST in class Test in

class Test
  CONST = 7
end

from outside of the class, I have to do this:

puts Test::CONST

Why do I get an error when I do this?

puts obj::CONST

If obj is an object of the Test class, why do I get an error if I try to access the constant through the object?

Answer 1

因为实例对象和类对象不是一回事。命名空间存在于类对象上，不存在于实例上。

但是，您可以向实例询问它的类，然后深入研究。

puts obj.class::CONST