From: Adam Shelly <adam.shelly@...>
Date: 2005-09-07T03:26:30+09:00
Subject: Re: beginners YAML question

On 9/2/05, daz <dooby@d10.karoo.co.uk> wrote:
> In short, @size is an attribute of Box ... but you're
> using the inherited Array#to_yaml to serialise your object.
> 
> Some pointers ...
> 
> 1) By defining an initialize method in Box, you /override/
>    the Array initialize - so, an empty Array is allocated.
>    To fix this, you need to call "super" (see 2)

Right. 

> 
> 2) Array already has a size attribute, so this works:
> 
'size' was an extremely bad choice of attribute name.  I was trying to
reduce my complex real code to a simple example, but I oversimplified.

> 3) Note that if you /don't/ inherit from Array...

But I do want to inherit from Array...
>
> 4) If you want Box to behave like an Array but with
>    attributes of its own, there are ways.
>    Ask again (giving details) if you need help with
>    that or any other aspect.
> 

That's exactly what I want.  A "Box" object which acts like an array,
but has other attributes too:
For example:

class Box< Array
    def initialize label, location, initial_size = 0, initial_value =
nil, &block
        super initial_size, initial_value
        @label = label
        @loc = location
    end
    def location
        @loc
    end
    def move_to new_loc
        @loc = new_loc
    end
    def label
        @label
    end
    def look_at
        "This is a box with a label that says " + (@label || "_nothing_")
    end
end


box = Box.new("Books", "Hall Closet")
puts box.look_at
puts box.to_yaml

box2 = YAML::load(box.to_yaml)
puts box2.look_at
puts "ERROR: Box not reloaded correctly" unless box2.label == box.label

What I can't figure out is how to get the extra attributes in the
YAML.  Do I have to override the to_yaml method?


Thanks for the help.
-Adam