Groleo Marius schrieb:
> 
> class B
>     def fun_b
>         p "B"
>     end
> end
> 
> class A
>     b = B.new
> end
> 
> a = A.new
> a.b.fun_b
> 
> The part that bugs me is this error:
> ./test.rb:15: undefined method `b' for #<A:0xb7cafb24> (NoMethodError)
> 
> What is the way to code the above ideea, so that the last line would be correct.

Maybe this is what you want:

   class A
     attr_reader :b
     def initialize
       @b = B.new
     end
   end

Note that here each instance of A has its own instance of B, which might 
not be what you want.

Regards,
Pit