Design Patterns

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ASSOCIATION CLASSES ➠ Associations can also have attributes. ➠ Reasonable, if the attributes cannot be assigned to any of the classes involved in the association. Writes Student Exam Writes mark GENERALIZATION/SPECIALIZATION ➠ Classes correspond to types. ➠ Subclasses correspond to subtypes, not subsets. ➠ Specialization = ”is a” , but ”behaves as” , ”is a kind of” BachelorCourse MasterCourse subject 13 Course Personnel Student Constraint title name name pers.nr inscription_number salary {complete} specialization 15 Professor TeachingAssistent specialty AGGREGATION AND COMPOSITION are special associations. Room Wall The wall is a part of the room. If a part belongs to a whole and can only exist with that whole, then this is a composition relation. CONSTRAINTS Window Frame or ➠ Are conditions that must hold. ➠ Are written between “{}”. 14 Window Frame ➠ The example: “{complete}” means that no other subclasses of Course can exist. ➠ Meaning of constraints must be described informally. 16
Classifying, Describing, and Using <strong>Design</strong> <strong>Patterns</strong> TYPES OF DESIGN PATTERNS (TICHY)(1) • Coupling/decoupling patterns 17 System is divided into units that can be changed independently from each other e.g. Iterator, Facade, Proxy • Unification patterns Similarities are extracted and only described at one place. e.g. Composite, Abstract Factory • Data-structure patterns Process states of objects independently of their responsibilities e.g. Memento, Singleton 19 TYPES OF DESIGN PATTERNS (GOF) • creational concern the process of object creation • structural deal with the composition of classes or objects • behavioral characterize the ways in which classes or objects interact and distribute responsibility Second criterion: scope specifies whether the pattern applies primarily to classes or to objects. TYPES OF DESIGN PATTERNS (TICHY)(2) • Control flow patterns 18 Influence the control flow; provide for the right method to be called at the right time e.g. Strategy, Visitor • Virtual machines Receive programs and data as input, execute programs according to data e.g. Interpreter (Remark: no clear boundary to architectural styles) 20
Page 1 and 2: Design Patterns DESIGN PATTERNS: CH
Page 3: ASSOCIATIONS ➠ denote the relatio
Page 7 and 8: HOW MVC WORKS - AN OVERVIEW MVC CLA
Page 9 and 10: • Composite (picture) - defines b
Page 11 and 12: Known Uses • View-class in Model/
Page 13 and 14: Participants • Subject - knows it
Page 15 and 16: APPLICATION OF THE STRATEGY PATTERN
Page 17: ➠ We have presented and used the

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