Various ways to call various things in Ruby

It seems not easy, if not a total mess, to memorize the various ways to call various things in Ruby. By various ways, I mean the dot (.) and the double colon notation (::). And the various things include constants, class methods and instance methods. So a quick summary could be handy.

	class	instance
constants	Y	N
class methods	Y	N
instance methods	N	Y

	.	::
constants	N	Y
class methods	Y	Y
instance methods	Y	Y

The double colon notation is also known as the scope resolution operator. It looks to me like it works more with constants (given that class names and module names are themselves constants), while the dot notation is more in favor of methods, whether class methods or instance methods. Until otherwise told, I'm gonna keep my life simpler and train myself this way.

Also, hats off to these two posts:

http://stackoverflow.com/questions/2276905/what-does-double-colon-mean-in-ruby
http://stackoverflow.com/questions/18061941/dot-operator-vs-scope-resolution-operator-with-modules-in-ruby