The set of minimum requirements of OO-methodology

Sometimes there is some confusion about what is required and what is optional, when one works with Object-Oriented methods either modelling or implementation.

I like to open your eyes to see clearly. One such thing to realize is that the benefits of  OO-method ( as well as Scum-method) is a step function.  This means that as long as we are moving below a certain threshold value, the corresponding function value is zero. These are like constitutional rights.

Description of business  domain in model or implementing that information system is when using  the Object Oriented Principles must include the following:

  1. All  describing structures of business  are always real or genuine objects or their associations.
  2. True object is one that has  life cycle. The moments in life cycle of an object are reflected by the values of  its attributes.
  3. All domain object have services of their own. This means that all the domain objects are “conscience” of their own state and they protect its integrity. In this way all the attributes within an object are always private and only visible to the object itself. By the way instead of “setters” of single attributes there should be only one method “setState()”.
  4. All business rules must be described and implemented in the services of these domain objects.
  5. The domain objects are allowed to reference only other domain object and nowhere else.

These are the core OO principles. Breaking any part of these will destroy totally the Object-Oriented approach.

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