From: Sam Kong <sam.s.kong@...>
Date: 2005-11-11T08:57:14+09:00
Subject: A question about class variable

Hello!

I have a question about class variable.

class C1
  @@a = "C1"
  def f
    @@a
  end
end

class C2 < C1
  @@a = "C2"
end

puts C2.new.f   #=> "C2"

It's understandable.
When I called C2.new.f
the method f seems to find C2's @@a.

Now I removed @@a from C1.

class C1
  def f
    @@a
  end
end

class C2 < C1
  @@a = "C2"
end

puts C2.new.f
#Result: in `f': uninitialized class variable @@a in C1 (NameError)


Why does it bother with C1's @@a if it returns C2's @@a?
I assume that the method f should behave polymorphically and the body
of f should be interpreted in the context of C2's instance method if I
call it via an instance of C2.
Probably I misunderstand something.
Can anybody enlighten me on this?

Thanks in advance.
Sam