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Transitional Page. Title: PATTERNS DESIGN. Design by: Zahid Iqbal . Definition:. - PowerPoint PPT PresentationTRANSCRIPT
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Title:PATTERNS DESIGN Design by:
Zahid Iqbal
“ Each pattern describes a problem which occurs over and over again in our averment, and then describes the core of the solution to that problem in such a way that you can use this solution a million times over without ever doing it the same way twice.”
Definition:
“Description of communicating objects and classes that are customized to solve a general design in a particular context [GOF].”
Definition2:
1979 - Alexander's timeless way of building 1987 - OOPSLA workshop by beck and ward 1995 - GOF ( Gamma, helm, Johnson, vlissides) - Design patterns ; Elements of reusable object- oriented software.
Historical perspective:
- STL (c++ template library)- Algorithms and data structure .- Object oriented analysis patterns [peter Coad]- Software idioms [coplien]- Antipatterns [brown]
Software patterns:
-Framework is a set of cooperative classes that makes up reusable design of a system.-Framework dictates the architecture of the software.
Frameworks:
Design patterns follow a certain structure (some or all).- Pattern name (and category)- Intent- Motivation- Applicability- Structure- Participants- Consequences
Design patterns:
- Implementation- Known uses- Related patterns
Design patterns:
Name - Meaningful phraseProblem - A statement of the problem which describes its intent ; the goals of objectives it wants to reach with in the given context and forces.
Design patterns:
Context -preconditions under which the problem and its solution seem to occur - the patterns applicability - May change over time.
Motivation:
- Static and dynamic relationship describing how to realize the pattern
- Instruction how to construct the work products - Picture diagram prose which highlight the pattern
structure participants and collaboration
solution
- One or more samples application to illustrate.• A specific context• How the pattern is applied Resulting context - the state or configuration after the pattern has been applied.- Consequences (good or bad) of the pattern
Example:
- Justification of the steps or rules in the patterns - How and why it resolves the forces to achieves the
desired goals principles and philosophies - How are he forces orchestrated to achieve
harmony- How does the pattern work
Rationale
- The static and dynamic relationships between this
patterns and other patterns known uses- To demonstrate that this is proven solution to a
recurring problem.
Related patterns
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