Object Analysis Classification

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Classification

Is the process of checking to see if an object belongs to a category or class, is regarded as a basic attribute of human nature.

Classes are an important mechanism for classifying object.

The role of a class is to define the attributes, methods and applicability of its instances.

Classification is concerned more with identifying the class of an object the individual objects within a system.

Example: defines the property color.

The problem of classification may be regarded as one of discriminating thing, not between the individual objects but between classes, via the search for features or invariant attributes or behaviors among members of a class.

Classification can be defined as the categorization of input data(things) into identifiable classes via the extraction of significant features of attributes of the data from a background of irrelevant detail.

Martin and Odell explain that classes are important because they create conceptual building blocks for design systems.

Identifying Classes

Four alternative approaches for identifying classes.

• Noun phrase approach,

• Class patterns approach,

• Use case driven sequence /collaboration modeling approach,

• Classes, Responsibilities and Collaborators(CRC) approach.

The first two approach have been included to increase your understanding of the object.

The unified approach uses the use case driven approach for identifying classes and understanding the behavior of objects.

Another approach that can be used for identifying classes is classes, responsibilities and collaborators developed by Cunningham, Wilkerson, and Beck.

Classes, responsibilities and collaborators more than technical then method, is used for identifying classes responsibilities and therefore their attributes and methods.

Noun Phrase ApproachA group of words used to form a basic name when it is:

Noun in the textual description are considered to be classes and verbs to be methods of the classes.

• Impractical to employ a single noun word.

• When a single noun would have too broad a concept if used as a basic name for example, 'machine' and 'board‘.

All plural are changed to singular, the nouns are listed , and the list divided into three categories

Relevant classes

Fuzzy classes

Irrelevant classes

Examples of the noun phrase :

The Chairman of the Board of Governors

The new vitamin packed high calcium low fat breakfast cereal

The crimson, ermine trimmed, velvet gown with gold trimmings was worn by Anne Boleyn at her coronation

of the noun phrase :•The Chairman of the Board of Governors•The new vitamin packed high calcium low fat breakfast cereal•The crimson, ermine trimmed, velvet gown with gold trimmings was worn by Anne Boleyn at her coronation

Examples of the noun phrase :

Classes from Relevant and Fuzzy Categories

Relevant classes have a purpose, they are clearly defined and so they are necessary.

Fuzzy classes, fuzzy classes are those classes which we are not sure about.

Redundant classes:

Don’t keep two classes that express the same information.

If more than one word is being used to describe the same idea, select the one that is most meaningful in the context of the system.

Irrelevant classes: Each class should have a purpose.

Each class must have a purpose and every class should be clearly defined and necessary.

A statement of purpose for each candidate class must be formulated.

If it cannot be done then eliminate that candidate class.

Attribute classes: Tentative objects that are used only as values should be

defined as attributes and not as a class.

Example for Client status and Demographic of Client are not classes but attributes of the Client class.

Adjectives classes: If the object behave differently when the adjective is applied

then make a new class.

It can used many ways

An adjective can suggest a different kinds of object,

different use of the same object, or it could be utterly irrelevant.

Does the object represented by noun behave differently.

Example:

The ViaNet collage management system:

Initial list of noun phrase:

NameAddressAgeMarkParent nameBranchDepartmentYearNot qualifiedQualifiedBrightAveragefee

WeekSem markSem feeScholarshipRefund amount

To eliminate the irrelevant classes: Bright, average, and week ere eliminate.

NameAddressAgeMarkParent nameBranchDepartmentYearNot qualifiedQualifiedFee

Sem markSem feeScholarshipRefund amount

Redundant classes: Same concept are refer so it is eliminate to sem mark NameAddressAgeMarkParent nameBranchDepartmentYearNot qualifiedQualifiedFeeSem feeScholarshipRefund amount

Reviewing the possible attributes: Revised list of candidate classes. Eliminate sem fee

NameAddressAgeMarkParent nameBranchDepartmentYearNot qualifiedQualifiedFeeScholarshipRefund amount