Implementing Presentation Logic

From: Shane Mingins (shanemingins_at_yahoo.com.clothes)
Date: 10/21/03

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    Date: Tue, 21 Oct 2003 11:53:06 +1300

    Hello

    I am working through how to implement some presentation logic. The
    situation is this:

    When editing an a certain object, the User Interface (UI) will display two
    lists to the user. Using ADD and REMOVE buttons the user is able to move
    items from one list to the other and vice-versa, for the object being
    edited.

    List One List Two
     A ADD>> E
     B <<REMOVE F
     C
     D
     G
     H
     ...

    >From the Presentation perspective it needs to be able to do the following:

    1. Load List One from a master list from the model layer.
    2. Load List Two from the object being edited from the model layer.
    3. Remove items from List One that are already in List Two.

    So if the master list was a list of letters A-Z and the object being edited
    has a letter list with E and F in it then the List One will not show E and F
    as available items and List Two will .... as pictured above

    Each item added or removed from List Two is what I am interested in. The
    add/remove will update the list for the object being edited (the model).
    The state of List One is only relevent to the current presentation state.

    <breakpoint> Is my explanation satisfactory? Does the terminology I use
    sound okay? </breakpoint>

    So now I am thinking that I can create a Presentation Class that will
    represent the fact that I have two lists that I wish to add/remove things
    from with the state of List Two also updating the model.

    IOW if the UI sends a message to add 'G' to List Two then the Presentation
    object will remove 'G' from List One and add it to List Two and send a
    message to the input controller object to add 'G' to the list of the object
    being edited in the model layer.

    How does that sound?

    Thanks
    Shane 

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