Why is this publicly accessible in my example: "MySymbol::TABLE"

Question

class MySymbol
  TABLE={}
  def initialize(str) @str = str end
  def to_s() @str end
  def ==(other)
    self.object_id == other.object_id
  end
end

class String
  def my_intern
    table = MySymbol::TABLE
    unless table.has_key?(self)
      table[self] = MySymbol.new(self)
    end
    table[self]
  end
end

"foo".my_intern

In the example above, which I found on a blog, I understand that TABLE is a hash and is a member of the MySymbol class. What I don't understand is how it can be accessed publicly from inside the String class. I thought class instance variables are private by default and you need to use get/set methods to access them from outside the class?

Answer 1

In your example, TABLE is a constant, not an instance (or class) variable (i.e. not prefixed wit @.)

Also, instance variables are not "private by default" (e.g. as is the case with C++ classes), although it may superficially look that way; they are simply not accessible outside the class by design, not because they are "private" (you cannot make them "non-private".)

Cheers, V.