Re: Aggregation by Logical containment

From: Robert C. Martin (unclebob_at_objectmentor.com)
Date: 01/06/05

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    Date: Wed, 05 Jan 2005 17:31:39 -0600

    On 22 Dec 2004 05:46:25 -0800, "Vijay" <vij_singh@hotmail.com> wrote:

    >Sorry, I should have given an exmaple.
    >
    >I have been reading Booch's book on OOAD with application. One of his
    >example shows how there is no physical containment between
    >"Professional society" and its members i,e society doesn't owns its
    >members. I guess this kind of aggregation is called aggregation by
    >logical containment. And then he describes about the aggregation with
    >physical containment which can implemented using "by value" or "by
    >reference".
    >
    >Which lead to my question "Why do we have to identify logical
    >aggregation?" . The only reason I can think of is that it may be part
    >of the analysis phase when the ideas are still developing.

    Have you read Eric Evans' "Domain Driven Design"? I think this book
    will explain the concepts quite nicely.

    In short, though, logical containment means physical containment
    *somewhere*, we just don't quite know where yet. By the time the
    program is implemented all the "logical containment" relationships
    will be replaced by physical containments.

    -----
    Robert C. Martin (Uncle Bob) | email: unclebob@objectmentor.com
    Object Mentor Inc. | blog: www.butunclebob.com
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    "The aim of science is not to open the door to infinite wisdom,
     but to set a limit to infinite error."
        -- Bertolt Brecht, Life of Galileo

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