1) Restructuring involves transforming a program to fit current needs rather than just changing external behavior like refactoring does. 2) Software should be habitable and find the right place for everything, so take a critical look at design issues like God classes and feature envy. 3) Common restructuring techniques include splitting God classes, removing middlemen, eliminating duplicate code, and moving behavior closer to data.

1. Restructuring
Tudor Gîrba
www.tudorgirba.com

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6. Restructuring is often taken
as a synonym of refactoring

7. Refactoring is a disciplined
technique for restructuring an
existing body of code, altering its
internal structure without
changing its external behavior

8. Refactoring is
behavior-preserving
transformation

9. Restructuring is transforming
a program to fit current needs

10. Why?
{ {
What?
{ { {
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}
} restructuring } }
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11. Software should be
habitable

13. The secret to tidiness is to have a
place for every thing
Denker
Markus

14. The secret to tidiness is to find the right
place for every thing
Denker
Markus

15. If it stinks, change it
Be ck
Gr andma

16. How?
Why?
{ {
What?
{ { {
{
} { {
}
} restructuring } }
} { } } }

18. Take a critical look at design

19. A God Class centralizes too much intelligence
Class uses directly more than a
few attributes of other classes
ATFD > FEW
Functional complexity of the
class is very high
AND GodClass
WMC ! VERY HIGH
Class cohesion is low
TCC < ONE THIRD
006
ari nescu 2
L anza, M

20. ModelFacade
from ArgoUML

21. p God Class
Split u
ModelFacade
from ArgoUML
2
er etal 200
Demey

22. d than done
Easi er sai
2
er etal 200
Demey

23. also w rap it
You can
2
er etal 200
Demey

24. you do not
Maybe uch it at all
need to to
God Class
in the last version
isGodClass(last)
AND Harmless God Class
Stable throughout
the history
Stability > 90%
4
Ratiu etal, 200

25. Client Provider
service()

26. Client Intermediary Provider
getProvider() service()

27. Client Intermediary Provider
getProvider() service()
this.intermediary.provider.service();

28. Provider2
service2()
Client Intermediary Provider
getProvider() service()
Provider3
service3()
this.intermediary.provider.service();
this.intermediary.provider2.service2();
this.intermediary.provider3.service3();

29. Provider2
service2()
Client Intermediary Provider
getProvider() service()
Provider3
service3()
this.intermediary.provider.service();
this.intermediary.provider2.service2();
this.intermediary.provider3.service3();
to str angers
eter : D on’t talk
of Dem
T he Law

30. Code
te Nav igation
E limina Provider2
service2()
Client Intermediary Provider
fullService() service()
Provider3
service3()
this.intermediary.fullService();
2
er etal 200
Demey

31. ge inte rfaces
ad to hu
t: This can le Provider2
Cavea service2()
Client Intermediary Provider
fullService() service()
Provider3
service3()
this.intermediary.fullService();
2
er etal 200
Demey

32. Middl e Man
R emove Provider2
service2()
Client Provider
service()
Provider3
service3()
this.provider.service();
this.provider2.service2();
this.provider3.service3();
Fow ler 1999

33. An Envious Method is more interested
in data from a handful of other classes
Method uses directly more than
a few attributes of other classes
ATFD > FEW
Method uses far more attributes
of other classes than its own
AND Feature Envy
LAA < ONE THIRD
The used quot;foreignquot; attributes
belong to very few other classes
FDP ! FEW
006
ari nescu 2
L anza, M

35. ser to Data
Behavi or Clo
Move

36. Data Classes are dumb data holders
Interface of class reveals data
rather than offering services
WOC < ONE THIRD
AND Data Class
Class reveals many attributes and is
not complex
006
ari nescu 2
L anza, M

38. ser to Data
Behavi or Clo
Move

39. Significant Duplication
006
ari nescu 2
L anza, M

40. A A
m1
m1'
m3
m2
m2'
6
ne scu 200
Lanza, Mari

41. A A
m3
B C B C
m1 m2 m1 m2
6
ne scu 200
Lanza, Mari

42. Restructuring can also improve performance

43. BusinessObject
Client BusinessSessionBean
BusinessEntityBean

44. BusinessObject
SessionFacade
Client BusinessSessionBean
BusinessEntityBean
java .sun.com

45. ModelFacade
from ArgoUML
es are good,
Not al l Facad od :)
some are G

46. Trouble never comes alone
Ano nymous

48. Redistribute Transform conditionals
responsibilities to Polymorphism
Eliminate Split up Transform Client ...
Navigation Code God Class Type Checks
Move Behavior Introduce Null Object
Closer to Data

49. es pro blems
ode co rrelat
inC

52. When?
How?
Why?
{ {
What?
{ { {
{
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}
} restructuring } }
} { } } }

53. Restructure all the time

54. Restructure all the time
his fea sible?
… hm m, is t

56. It is feasible

57. Development Maintenance

59. are evolution
Softw

60. Tudor Gîrba
www.tudorgirba.com
creativecommons.org/licenses/by/3.0/