Re: OOP/OOD Philosophy

On 9 Jul 2005 05:29:08 -0700, "frebe" <fredrik_bertilsson@xxxxxxxxxxx>
wrote:

>> Now imaging that deep within the database structure we add a new
>> column to a relationship table. This column modifies the way the
>> relationship works.
>
>Your initial statement didn't say anything about modifying primary or
>foreign keys. You said "add a new column". If you change a primary or
>foreign key, the GUI will not be unaffected. Can you give some example
>of primary or foreign key change, that can be isolated to only the
>persitence layer?
>
>> Let's finally say that the GUI code depends deeply on the database
>> schema, but the necessary 'if' statement to check the new field of
>> that relationship table was not put into the GUI code.
>> The GUI crashes.
>
>Can you give an example? I am not sure I understand why the GUI would
>crash.

The new structure of the database introduces a logical flaw in the
calculations within the GUI. The GUI code inadvertently frees an
allocated structure *twice*. The heap gets corrupted. A billion
instructions later the GUI crashes.

However, let me say that when I used the term "crash" in the original
post, I simply meant "malfunction".


-----
Robert C. Martin (Uncle Bob) | email: unclebob@xxxxxxxxxxxxxxxx
Object Mentor Inc. | blog: www.butunclebob.com
The Agile Transition Experts | web: www.objectmentor.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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