Refactorings of Design Defects using Relational Concept Analysis

1. Refactorings of Design Defects usingRefactorings of Design Defects using
Relational Concept Analysis
Naouel Moha, Amine Mohamed Rouane Hacene,
LORIA, France
Petko Valtchev, and Yann-Gaël Guéhéneuc
DIRO, University of Montréal, Canada
LATECE, Université du Québec à Montréal, Montréal, Canada
ICFCA’08
Montréal (Qc), Canada, February 25-28, 2008

2. Context
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3. Context
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4. Context
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5. Context: Overall Process
Textual descriptions
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of design defects
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Classes having
design defects
Better
Design

6. Context: Overall Process
Textual descriptions
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Classes having
design defects
Better
Design

7. Context: Overall Process
1-2. Specification and Detection of DDs
More and more tools and techniques
Actively researched area
Method DECOR (Defect dEtection for CORrection) [Moha 06]
3 S ti3. Suggestion
Manual identification of the modifications
Time-, resource-consuming, error-prone activity, g, p y
4. Correction
Refactoringsg
Technique used to change “the internal structure of software to make it
easier to understand and cheaper to modify without changing its
observable behavior”
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8. What Kind of Defects ?
Design Patterns are “good” solutions to recurring design problems
Design Defects (DDs)
are “bad” solutions to recurring problems, Antipatterns [Brown 98]
hi d d l t d i t b ki h d thinder development and maintenance by making programs harder to
comprehend and/or evolve
DDs of interest: infected by low cohesion and high couplingDDs of interest: infected by low cohesion and high coupling
Cohesion: how closely the methods are related to the variables in
the class
Coupling: the degree of its reliance on services provided by other
classes
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9. What Kind of Defects ?
An example of DDs [Brown 98]
Blob (God Class)
“ Procedural-style design leads to one object with a
lion’s share of the responsibilities while most other
objects only hold data or execute simple processes ”
Large controller class
Many fields and methods with a low cohesion
High coupled with the data stored in
associated data classes
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10. An Example
Blob
Before
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11. An Example
H t t th d f t ?How to correct the defect ?
Before After
Large class becomes less complexLarge and complex class
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Data classes gain more behaviour
More object-oriented style
Small data classes
Not object-oriented

12. An Example
R di t ib t l b i ti l ( ith iblRedistribute class members among existing classes (with possibly
new classes) to increase cohesion and–or decrease coupling
Before After
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13. Contribution
Suggestion
RCA [Rouane 07, Ph.D. Thesis]
E i f FCA l i l dExtension of FCA to relational data
Models the inter-object links and infers description logics role like
relations between concepts
RCA provides a suitable framework for clustering individuals along
the properties they share and their links with other individuals
Identify methods that share common fields and methods that call
common methods cohesive sets low coupled
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14. Contribution
Suggestion
RCA [Rouane 07, Ph.D. Thesis]
E i f FCA l i l dExtension of FCA to relational data
Models the inter-object links and infers description logics role like
relations between concepts
RCA provides a suitable framework for clustering individuals along
the properties they share and their links with other individuals
Identify methods that share common fields and methods that call
common methods cohesive sets low coupled
D l t t d h f ti d f t« Develop an automated approach for suggesting defect-
correcting refactorings using RCA »
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15. An Example
H t t th d f t ?How to correct the defect ?
Before After
Large class becomes less complexLarge and complex class
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Data classes gain more behaviour
More object-oriented style
Small data classes
Not object-oriented

16. An Example
H t t th d f t ?How to correct the defect ?
Cohesive SetsBlob
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17. An Example
H t t th d f t ?How to correct the defect ?
I = {W-borrow_date_Book, W-return_date_book}
E = {}
I = {call:c4}
I = {‘check_Availability_Book()’}
E = {check_Availability_Book()}
E {}
I = {‘reserve_Book()’, W-reserved_book}
E = {reserve_Book()}
I = {‘borrow_Book()’}
E = {borrow_Book()}
I {call:c4}
E = {}
Lattice Cohesive Set
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18. An Example
H t t th d f t ?How to correct the defect ?
Cohesive Sets After Refactoring *
* Move Method Mode Field Create Class
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Move Method, Mode Field, Create Class

19. Suggestion
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20. Suggestion
1. RCF Modeling
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21. Suggestion
RCA Al ith2. RCA Algorithms
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22. Suggestion
RCA Al ith2. RCA Algorithms
I = {W-library opened}
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I {W library_opened}
E = { }
I = {‘open_Library()’}
E = {open Library()}
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I = {‘close_Library()’}
E = {close_Library()}
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E {open_Library()}
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23. Suggestion
RCA Al ith2. RCA Algorithms
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24. Suggestion
RCA Al ith2. RCA Algorithms
I = {‘check_Availability_Book()’}
E = {check_Availability_Book()}
4
I = {call:c4}
E = { }
19
I = {‘reserve_Book()’,W-reserved_book}
E = {reserve_Book()}
12
I = {‘borrow_Book()’}
E = {borrow_Book() }
3
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25. Suggestion
3. Interpretation
Cohesive Sets After RefactoringCohesive Sets After Refactoring
* Move Method Mode Field Create Class
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Move Method, Mode Field, Create Class

26. Experimental Study
Tooling
PADL to model source code and generate contexts
Galicia to construct and visualize the concept lattices
E i tExperiments
Goal: evaluate the relevance of the cohesive sets suggested
4 different open-source programs
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27. Experimental Study
Precision
Nb of real
cohesive
sets
Nb of
cohesive
sets
Nb of fields/
methods
moved
Size (fields +
methods)
LOCBlob Class
System
70%710(27+32) 59(42+66) 1082,049DHTTransportUDPImpl
Azureus
V2.3.0.6
58%1119(35+62) 97(47+80) 1271,868DHTControlImpl
31%516(24+33) 57(36+47) 831,393TRTrackerBTAnnouncerImpl
55%1731(23+85) 108(29+105)1341,142LogBrokerMonitor
Log4j
V1.2.1
50%918(8+44) 52(9+53) 62387Category
50%24(5+30) 35(7+52) 59236IndexReader
ene
.4
Luce
V1
77%1013(24+37) 61(36+48) 84829QueryParser
50%918(17+25) 42(24+35) 59710FSNamesystem
Nutch
V0.7.1
73%811(17+18) 35(22+31) 53555JobTracker ( )( )
57%Average Precision:
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28. Conclusion
Contribution
an approach that uses RCA to suggest refactorings to correct
certain DDs in particular Blobcertain DDs, in particular Blob
Validation
4 different programs
Relevant refactorings to improve programs
Future Work
- Generalise to other DDs
Assess more programs via our approach- Assess more programs via our approach
- Discuss the suggested refactorings with their developers and
apply them
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29. Questions
Contact: mohanaou@iro.umontreal.ca
http://www-etud.iro.umontreal.ca/~mohanaou
Thanks for your attention !
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Thanks for your attention !