1. The document discusses principles of emergent design including contextual force, patterns, commonality variability analysis, and programming by intention. 2. Commonality variability analysis involves identifying what is common and what varies across different contexts for a given problem. 3. Programming by intention focuses on conceptualizing what you want to do at a high level before implementing technical details.

1. Coding Defines Reality
Code Mania #101
@varokasBIGBEARS.

3. Design

4. Design
Creating Solutions based on
1. Requirements
2. Desired Properties

5. • Available
• Reliable
• Performance
• Maintainable
• Reusable
• Usable

8. Design is very easy
Knowing what you want is very hard

9. Christopher Alexander

10. Christopher Alexander

11. Principles of Emergent
Design

12. Contextual Force

13. Force
Force
Force
Force
Force
Force
Force ForceDesign

14. Force Force
Force
Force
Force
Force
Force
Force
Design

15. –Johnny Appleseed
“Type a quote here.”Force Force
Force
Force
Force
Force
Force
Force
Design

20. Feel the force!
Do not put in one that does not exist

21. Patterns

22. Design Patterns

23. Patterns
•

24. “The Pattern is in the
problem”

25. –Johnny Appleseed
“Type a quote here.”
Pattern
Problem

26. “Don't Solve the Problem. Discover the
Pattern”

27. Emergent Design
Change from Create Solutions
to Discover Solutions

28. Discovering Techniques
• Code Properties Analysis
• Commonality Variability Analysis
• Programming by Intention
• Tests (TDD)

29. Commonality
Variability
Analysis

30. Commonality
Variability
Analysis
• What is in Common?
• What Varies?
• Under a certain Context of Use

31. CVA Example (non-software)

32. CVA Exercise (Pen-Pencil)
Pen
• write with ink
• can't erase
Pencil
• write with lead
• can erase
?
• write
• cylinder
• can put in a box
• breakable
• ....

33. CVA Exercise (Pen-Pencil)
Pen
• write with ink
• can't erase
Pencil
• write with lead
• can erase
WritingTool
• write
• cylinder
• can put in a box
WritingUser

34. CVA Exercise (Pen-Pencil)
Pen
write() {
//inkImpl
}
Pencil
write() {
//leadImpl
}
WritingTool
write()
WritingUser

35. CVA Exercise (Pen-Pencil)
Pen
write() {
//inkImpl
}
Pencil
write() {
//leadImpl
}
WritingTool
write()
interface WritingTool {
def write()
}
class Pen extends WritingTool {
def write() {
//ink impl
}
}
class Pencil extends WritingTool {
def write() {
//lead impl
}
}

36. CVA Exercise (Pen-Pencil)
Pen
write() {
//inkImpl
}
Pencil
write() {
//leadImpl
}
WritingTool
write()
WritingUser

37. CVA Exercise (2)
• There are two types of shape (Circle, Square)
• There are two types of writer (Pen, Pencil)
• Each shape can print itself on different writers

38. CVA Exercise (2)
Pen
write() {
//inkImpl
}
Pencil
write() {
//leadImpl
}
Writer
write()
• There are two types of
shape (Circle, Square)
• There are two types of
writer (Pen, Pencil)
• Each shape can print
itself on different writers

39. CVA Exercise (2)
Pen
write() {
//inkImpl
}
Pencil
write() {
//leadImpl
}
Writer
write()
Square
Shape
• There are two types of shape (Circle, Square)
Circle

40. CVA Exercise (2)
Pen
write() {
//inkImpl
}
Pencil
write() {
//leadImpl
}
Writer
write()
Square
Shape
print()
• Each shape can print itself on different writers
Circle

41. Programming by Intention
• "So what do we want to do"?

42. Perspective
• Conceptual
• Specification
• Implementation

43. Starbucks
• Create a software for cashier and barista
• A program accepts order from user
• Retrieve cost based on the order
• A program shows the barista what to do

44. Starbucks
• A program creates
order from user
• Retrieve cost based
on the order
• A program shows
the barista what to
do
order = user.createOrder()
cost = order.getCost()
inst = order.whatToDo()

45. Starbucks
• Select Size of cup (S,M,L)
• (S) Cup -> Coffee
• (M) Cup -> Coffee x 2
• (L) Cup -> Coffee x 3
• S = 100, M = 120, L = 150
order = user.createOrder() {
selectSize()
}
cost = order.getCost()
inst = order.whatToDo()

46. Starbucks
• Select Size of cup (S,M,L)
• (S) Cup -> Coffee
• (M) Cup -> Coffee x 2
• (L) Cup -> Coffee x 3
• S = 100, M = 120, L = 150
M
coffee() {
//2
}
price() {
//120
}
Cup
coffee()
price()
S
coffee() {
//1
}
price() {
//100
}
L
coffee() {
//3
}
price() {
//150
}

47. Starbucks
order = user.createOrder() {
selectSize()
}
cost = order.getCost() {
order.getCup().getPrice()
}M
coffee() {
//2
}
price() {
//120
}
Cup
coffee()
price()
S
coffee() {
//1
}
price() {
//100
}
L
coffee() {
//3
}
price() {
//150
}
Order

48. Closing Thoughts

49. When does design starts?
When does it end?

51. `
http://askmissa.com/wp-content/uploads/2011/10/
photo5.jpg
http://en.wikipedia.org/wiki/
File:Space_Needle_2011-07-04.jpg
http://sherrlock.files.wordpress.com/2011/06/space-
needle-elevationsweb1.jpg?w=500&h=540

53. Happy Coding! (Designing)

54. Other slides

55. Starbucks (v2)
• Select Coffee Type (Hot/Cold) [ cold serve with ice ]
• Select Size of cup (S,M,L)
• (S) Cup -> Coffee
• (M) Cup -> Coffee x 2
• (L) Cup -> Coffee x 3
• S = 100, M = 120, L = 150, Hot/Cold = Same price

56. Starbucks (v3)
• Select Coffee Type (Hot/Cold) [ cold serve with ice ]
• Americano [ Coffee + Water ]
• Cappuccino [ Coffee + Milk + Whip the milk ]
• Latte [ Coffee + Milk ]
• Select Size of cup (S,M,L)
• (S) Cup -> Coffee
• (M) Cup -> Coffee x 2
• (L) Cup -> Coffee x 3
• S = 100, M = 120, L = 150, Hot/Cold = Same price, Latte +10, Cappucino + 20