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انتزاع و هزینه - انتزاع و تاثیرات آن در توسعه و نگهداری نرمافزار
- 3. CHANGE
- 4. Cost An amount that has to be paid or spent to buy or obtain something.
- 6. —Structured Design “The goal of software design is to minimize the cost of software and maximize the value”
- 9. —Manny Lehman “E-Type program is software that isn't ever done and changes, and needs to change constantly. This is because of it's specification and requirements change constantly.”
- 10. Cost Of Software cost(change) cost(software) ~= cost(change) ~= cost(big changes) cost(big change)
- 11. Coupling The degree of interdependence between software modules; a measure of how closely connected two routines or modules are; the strength of the relationships between modules.
- 12. Cost Of Software cost(change) cost(software) ~= cost(change) ~= cost(big changes) cost(big change) ~= coupling
- 14. — Coupling “Don't throw us away“
- 15. Abstraction Abstraction, in the common natural language sense, means to focus on the general and put aside the specific. we abstract by emphasizing what is common and deemphasizing details.
- 16. The Gang of 4 recommended that we design to interfaces, which is another way of saying that relationships between entities should be established at the abstract level.
- 17. —Some one “Abstractions have run time, compile time and human costs“
- 18. —Sandi Metz “Duplication is cheaper than the wrong abstraction”
- 19. —Manny Lehman “E-Type program is software that isn't ever done and changes, and needs to change constantly. This is because of it's specification and requirements change constantly.”
- 20. Chess Eight Queens Puzzle Lehman's laws S-Programs E-Programs Real-world activity P-Programs S P E
- 21. How do we use abstractions safely?
- 22. A way can help you to find a good Abstraction
- 24. Commonality Variability Analysis a strong way to determine how a set of family members might abstractly be considered the same, and then went on to suggest that variability analysis could be performed within the context of a given abstraction to determine how they were different.
- 25. Commonality Analysis Commonality analysis is the search for common elements that helps us understand how family members are the same.
- 26. Finding the domain is the first step of CVA
- 27. Variability Analysis Variability analysis expresses what is not common between a family members.
- 28. —Soheil Karami “A Bounded Context and Subdomain are indeed a form of abstraction”
- 29. —James Coplien “Grouping by commonality naturally leads to chunks that are independent of each other because each chunk has low commonality with the elements in other chunks”
- 30. CVA Supports Abstraction 01 02 Reduces Coupling 03 Reduces Maintenance Cost
- 33. Show PDF files
- 37. —Soheil Karami “Don't use your implementation as an abstraction“
- 39. List<T>
- 42. Your last favor
- 43. Summary The cost is our concern. 01 02 Wrong abstraction makes our life difficult. 03 Do CVA continually.
- 44. THANKS!