A summary of public, private, and protected differences in Ruby _ruby topics

Focus on private and protected

Public

The default is public, the global can be accessed, this does not explain

Private

C + +, "private" means "private to this class", but Ruby is the "private to this instance".
In C + +, for Class A, you can access the private method of A's object as long as you can access Class A.
Ruby, but not: You can only access this object's private method in the instance of your object.
Because Ruby's principle is "private means you cannot specify a method recipient," the receiver can only be self, and self must omit!
So the Ruby Neutron class can access the private method of the parent class. But Self.private_method is wrong.

Protected

can be accessed in this class or subclass, and not in other classes.

Test code (accessible by public, slightly code)

Class A
 def Test
  protected_mth
  private_mth
 
  self.protected_mth
  #self. private_mth   #wrong
 
  obj = b.new
  obj.protected_mth
  #obj. private_mth    #wrong
 end
 
 protected
 def protected_mth
  puts "#{self.class}-protected"
 end
 
 private
 def private_mth
  puts "#{ Self.class}-private "End"
 
class B < A
 def Test
  protected_mth
  private_mth
 
  self.protected_mth
  #self. private_mth   #wrong
 
  obj = b.new
  obj.protected_mth
  #obj. Private_ MTH    #wrong
 end
 
class C
 def test
  a = A.new
  #a. protected_mth     #wrong
  #a. private_mth      #wrong
 end
 
a.new.test
b.new.test
c.new.test

Note: Ruby's access control is different from Java, and there is no packet difference.
Classes in other packages simply reference the target class and are the same as the class access control rules under the target-like package.