From: Ye Dingding <yedingding@...>
Date: 2007-09-03T18:11:20+09:00
Subject: Re: How to extend a method?

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Thanks. Maybe using ExtendA module is a good start, :)

I don't want to rewrite A class directly, but i want to extend it in my app=
.
Indeed, i want to extend Rails::Initializer, and when i start
a rails app, it can initialize the variable automatically.

Module R
    class A
        attr_accessor :b

        def  self.run
           init =3D new B
           init.send(:process)
        end

        def process
           initize_a
        end

        def initize_a
           # other action using a.
        end
    end

    class B
        attr_accessor :a

        def initialize
           self.a =3D 'a'
        end
    end
end

I want to add a variable 'b' and initialize it when new a B. And then do
initialize_b when executing A#process.

Module R
     class A
       def initialize_b
       end
     end
end

I think Moduel ExtendB(as what you said) can be used to add a variable 'b'
and set the instance value.
But how can i directly initialize_b when executing A#process? I used to get
a A object and then invoke the initialize_b method.
But i didn't like that way? Is there a better way to directly inject the
code to the A#process?

Thank you.


On 9/3/07, Florian A=DFmann <florian.assmann@email.de> wrote:
>
> Florian A=DFmann schrieb:
> > Subclass C:
> >
> > class B < A
> >   attr_accessor :b
> >   def intialize
> >     super # calls parent class (A) that already initializes @a
> >     @b =3D 'b'
> >   end
> > end
> >
> > Regards
> > Florian
> >
> >
>
> module ExtendA
>   attr_accessor :b
>   def self.included(base)
>     base.instance_variable_set :@b, 'b'
>   end
> end
>
> class A
>   include ExtendA
> end
>
> # There are probably 10^x ways to do this...
>
> Regards
> again
>
>
>

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