From: matt@... (matt neuburg)
Date: 2009-05-12T22:40:08+09:00
Subject: Re: inheritance in ruby

jarodzz <jarodzz@gmail.com> wrote:

> class Page
>     @url=""
> 
>     def initialize
>         puts "going to "+@url
>     end
> end
> 
> class MainPage < Page
>     @url = "Main"
> end
> 
> class LoginPage < Page
>     @url = "Login"
> end

The problem is that the @url mentioned in the first line of each class
definition and the @url mentioned in the initialize method are not the
same. This is a common beginner mistake. The way to speak of an instance
variable is from inside an instance method (during code that runs inside
an instance). So:

class Page
    def initialize
        puts "going to "+@url
    end
end

class MainPage < Page
    def initialize
        @url = "Main"
        super
    end
end

class LoginPage < Page
    def initialize
        @url = "Login"
        super
    end
end

m.

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