OO Design?


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Thread: OO Design?

  1. #1
    Todd W Guest

    OO Design?


    OO Design Question...

    I've written some objects before but never a completely OO program. This
    will be my first stab. I'm in the analysis and design stage. The program
    itself is pretty simple. Basically, it reads data from a few text files
    created by some other program and then imports the data into an existing
    Excel spreadsheet. The text file has an unknown number of records. Each
    record has the following columns:

    - ClientNumber
    - ClientDescription
    - LastPayment
    - Amount1
    - Amount2
    - Amount3
    - Amount4
    - Amount5
    - Total

    So far, I'm planning to create an object to represent each file. And then
    a collection of child objects to represent each record within the each file.
    Assuming this is OK, I'm wondering how to implement the amount 1 - 5 fields.
    As you can see, these are repeated fields. What is the proper OO technique
    to represent repeated fields? I can think of three ways to implement this:

    A) Create a separate property for each amount:

    Private Property Get Amount1 As Currency
    End Property

    Private Property Get Amount2 As Currency
    End Property

    Private Property Get Amount3 As Currency
    End Property

    ...etc...

    B) Create an array of amounts:

    Private Property Get Amount() As Currency()
    End Property

    C) Create a collection of amounts:

    Private Property Get Amount() As Collection
    End Property

    Which is the correct OO way of doing this? BTW, these property(s) will be
    read only and FWIW I've been guaranteed that the file format will not change.

    Todd

  2. #2
    Colin McGuigan Guest

    Re: OO Design?

    Todd W wrote in message <39049c22$1@news.devx.com>...
    >
    >OO Design Question...

    <snip>
    >Which is the correct OO way of doing this? BTW, these property(s) will be
    >read only and FWIW I've been guaranteed that the file format will not

    change.
    >
    >Todd


    How do you feel about the possiblities of the file format changing in the
    future? If you believe that it won't, then I'd just go ahead and use the
    five distinct properties; kludgy, yeah, but quick, and it sidesteps some
    issues (what happens if this record only has four amounts in its
    collection?, etc). If you have the slightest glimmer that it's going to
    change down the line, though, I'd use a collection (as I find them easier to
    work with, and the code to be more readable, than arrays)

    --
    Colin McGuigan




  3. #3
    Anthony Jones Guest

    Re: OO Design?

    Todd,

    To be frank, the scenario you outlined doesn't really need the level of OO
    you're proposing. Consider using a single object to represent the file and
    have it behave more like a recordset. Another possibility is a single
    object that will perform the transform.

    As far as the Amount fields are concerned I would use:-

    Private Property Get Amount(Index as Long) as Currency

    --
    Anthony Jones
    Secta Group Ltd
    AnthonyWJones@msn.com



  4. #4
    Mario Lanza Guest

    Re: OO Design?


    Todd,

    The OO methodology is currently the best one we have in the industry for
    writing programs; HOWEVER, on occasion you should forego OO for old-style
    structured coding. Why?

    Classes are great. You design them to be flexible and reusable. Designing
    your classes with this in mind adds a little overhead to the design process--the
    extra thought is good overhead, really--but sometimes the solution you need
    is a quick and easy one and "structured" is the way to go. For simple, one-fuction
    programs which are not likely to grow, consider structured.

    As for your question: I think using a collection is more suitable for objects.

    Mario T. Lanza
    Metro Information Systems



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