Re: Arrays with records as objects

On Thu, Nov 22, 2012 at 8:37 AM, Steve Tucknott <[e-mail]> wrote:
> Robert
>
> The TodoItem class is as attached.
>
>
> I'm a complete novice, so I'm not sure how structures are used in Ruby -
> I had tried a simple case of '..build record...put in array' in another
> example where I built a local record and appended that to a local array,
> and then I accessed the array fields by a simple array[n].field1. So I
> stupidly assumed that the similar '@list << item_rec' would append the
> structure of item_rec in the list array.
>
> Attachments:
> http://www.ruby-forum.com/attachment/7888/TodoItem.rb

Steve,

I'm probably not understanding what you're trying to do here, but why
do you use the OpenStruct class here?

I think the question of how to access an anonymous object in an array
is still an interesting one. I think you have to give @item_rec
accessors (maybe just attr_reader? not sure). The attr_accessor's you
have set for :done, :action, and :name define instance variables
directly in TodoItem, but then you create a new object @item_rec and
assign instance variables to it. This results is your class really
having 4 instance variables, not 3, only 3 of which aren't being used:

TodoItem instance vars:
@done - not used by class
@action - not used by class
@name - not used by class
@item_rec - this is used

The object @item_rec points to has 3 instance variables:
@done
@action
@name

So, if you replace the attr_accessor line with:

attr_accessor :item_rec

Then, in your outer code, you can refer to it with the list as:

@list[0].item_rec.name

Still, unless this is an exercise in using OpenStruct, it's quite unnecessary.

Instead, you can simply do this:

 class TodoItem
    attr_accessor :done, :action, :name
    alias_method :done?, :done

    def initialize(line)
        # Create a record of state, action and name with state (done)
set to false
        # set state to undone
        @done  = false
        @action, @name   = line.split("<<>>")
	# Generally not a good idea to have object print out internal state like this
	# It can be useful for debugging, but better to define a
	# to_s method that will format it how you like it
        # STDOUT.puts "New TodoItem -  #{@item_rec}"
	# if this really is debugging info, consider using a
	# logger instead of tossing it to STDOUT
    end


    # maybe this is personal, but I'd call this state?
    # also, look at the ternary operator. the following could be written
    # @done ? "Done" : "Active"
    def state_getter
        if @done
            "Done"
        else
            "Active"
        end
    end

    # You might consider a more descriptive set of methods
    # that say what is happening, such as "complete" and "undo"
    # rather than the single method to flip the value.
    # flipping rather depends on the current state, obviously,
    # but it thus requires proper knowlege of the current
    # state to determine what to do. methods like "complete" and
    # "undo" state more clearly their intentions.
    def state_setter
        STDOUT.puts "Setter Status Was ("+@item_rec.done+") for
("+@item_rec.name+')'
        @item_rec.done = !@item_rec.done
        STDOUT.puts "Setter Status Now ("+@item_rec.done+") for
("+@item_rec.name+')'
    end

 end