From: ts <decoux@...>
Date: 2001-10-06T23:05:17+09:00
Subject: [ruby-talk:22159] Re: Variables, constants, and scopes in Ruby

>>>>> "A" == Alan Stern <stern@rowland.org> writes:

 Well, there are too many questions :-)

A> There must be separate name tables for local variables, instance
A> variables, class variables, and constants.  (As an example, each
A> object must contain a table of its own instance variables.  And I
A> assume each class object must contain a table of its class variables
A> -- is that so?)  At what times are these tables created?  Where are
A> they stored?  When do they get pushed/popped on the name-lookup stack?

 * local variable are resolved at compile time and stored in the def 

 * instance variable (and class variable) are stored in the object (with
some small exceptions) and are resolved via the inheritence mechanism

 * constant are stored in the object but don't follow the same resolution
   than instance variable. This give you the possibility to write

   module A
      class B
      end
   end

  B is in reality A::B. If the resolution was the same than for instance
  variable you must write (to have the same effect)

   module A
      class A::B
      end
   end

A> 	print "A instance variables: #{A.instance_variables}\n"

 You ask for variables with a name beginning with *only* one @

A> 	print "A class variables: #{A.class_variables}\n"

 You ask for variables with a name beginning with *two* @

A> Apparently there is special treatment for class variables.  So where do
A> they get stored?
 
 With the instance variables.


Guy Decoux