انتزاع، یکی از اساسی‌ترین ابزارهای انسان برای مواجهه با پیچیدگی است. انتزاع تشخیص شباهت‌های بین اشیا، پدیده‌ها و یا مفاهیم و تمرکز بر این شباهت‌ها و نادیده گرفتن تفاوت‌ها و جزییات غیر ضروری است. در این ارائه، به بررسی نقش انتزاع در طراحی و نگهداری نرم‌افزار می‌پردازیم و تلاش می‌کنیم تا نشان دهیم که انتزاع چگونه می‌تواند هزینه‌های نگهداری را کاهش و کیفیت نرم‌افزار را افزایش دهد. این ارائه قصد دارد تا نشان دهد که چگونه با استفاده از انتزاع صحیح در مساله می‌توان ساده‌تر با تغییرات همگام شد و به نیازهای جدید پاسخ داد.

1. Soheil Karami
ABSTRACTION
AND
COST

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”

7. Cost
in software development

8. Cost Of Software
cost(change)
cost(software) ~=

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

23. Commonality
Variability
Analysis

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

31. Sales Inventory
Delivery
Accounting Payment
KetabKade
Inventory
Inventory
Inventory
Others

32. Sales
Sales
Book
AudioBook
Item
Book
AudioBook

33. Show PDF files

34. Sales Inventory
Delivery
Accounting Payment
KetabKade
Inventory
Inventory
Inventory
Others

35. Delivery
Epub PDF
Content

36. Variability
Positive
01
02 Negative

37. —Soheil Karami
“Don't use your implementation as an
abstraction“

38. Delivery
Content
PDF
epub
Showable
PDF
epub
Playable
Audio

39. List<T>

40. Variability
Changeable Parts
V
Commonality
Stable Parts
C

41. Strategy Design Pattern

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!