1. Towards a Multi-paradigm Complexity Measure
Zoltán Porkoláb and Ádam Sillye
Department of Programming Languages and Compilers
Eötvös Loránd University, Faculty of Informatics
Budapest, Hungary
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2. The structure of the presentation
The role of the software metrics
Metrics: an overview
Object-oriented software metrics
Multiparadigm programming
The AV-graph
Empirical results
SPLST 2005 Tartu, Estonia

3. Role of software metrics
Cost of the software
Specification
Design
Implementation
Testing & Bug-fixing
Maintenance
More than 70% of cost is for testing and maintenance (Zuse 1998)
Software quality
SPLST 2005 Tartu, Estonia

4. Software metrics Software metrics:
Measuring the development process (process metrics)
Measuring the product (product metrics)
Product metrics:
External metrics:
Reliability metrics
Functional metrics
Efficiency metrics
Internal product metrics:
Size
Complexity
Style
SPLST 2005 Tartu, Estonia

5. Product metrics Size metrics: LOC, eLOC Ignore the semantics
Structural metrics:
McCabe 1976
Motivation: predict testing efforts
For structured programs: V(G) = p + 1
Howatt and Baker 1989
Motivation: involve nesting level
SN(G) = |N|+ND(G)
Kell? : V(G) = e – n + 2p ciclomatic number
SPLST 2005 Tartu, Estonia

6. Object-oriented metrics
Chidamber-Kemerer (1994) OO metrics suite:
WMC (Weighted Methods per Class)
DIT (Depth of Inheritance Tree, DIT)
NOC (Number of Child Classes)
CBO (Coupling Between Object Classes) fan-in and fan-out
RFC (Response for Class)
LCOM (Lack of Cohesion in Methods)
Chidamber - Kemerer
Henderson - Sellers
RFC: a hivo ill a hivott metodusok szama
SPLST 2005 Tartu, Estonia

7. Software paradigm evolution
Evolution of software paradigm
Non-structured programs (McCabe CCN)
Structured programming (+nesting level)
Object-oriented programming (OO Metrics)
Class, inheritance, virtual function
Generative programming
Aspect-Oriented (Kitzales 1994) ??
Template metaprogramming (Veldhuizen 1994) ??
Intentional programming (Simonyi 1995) ??
Java generics (Pizza, GJ: 199X, Java5: 2004) ??
SPLST 2005 Tartu, Estonia

8. Multiparadigm programming
Multiparadigm programming (Coplien 1998)
Different domains are described by different ways
Simultaneous usage of paradigms
The Challenge
How to compare programs written in different paradigms?
How to measure multiparadigm programs?
SPLST 2005 Tartu, Estonia

9. Paradigm-independent Software Metrics
Applicable for programs written in different paradigms or in mixed-paradigm environment
Based on general programming language features which are paradigm- and language-independent
The paradigm-dependent attributes are derived from these features
SPLST 2005 Tartu, Estonia

10. Components Control Structure of Program
Most of the programs share the same control statements
Complexity of Data Types
Reflects the complexity of data types used (like classes)
Complexity of Data Access
Connection between control structure and data
Direction of data flow
Nesting depth
SPLST 2005 Tartu, Estonia

11. AV-graph data node output node input node smain P1 tmain b P4 a c d1
SPLST 2005 Tartu, Estonia

12. AV-graph metrics = |A| + S (ND(G) + |L|) |N| number of nodes
nd(n) = | Pred(n) | nesting depth of node ‘n’
ND(G) = S nd(n) for all nodes
C(G) = |N’| + ND(G)
C(O) = |N’| + S ND(G)
= |A| + S (ND(G) + |L|)
SPLST 2005 Tartu, Estonia

13. Class Complexity Control structures
Complexity of method control structures
Complexity of data types
Local variables in methods
Attributes (could be complex types)
Coupling between classes
Inheritance
Complexity of data handling
Connection between control structure and data
SPLST 2005 Tartu, Estonia

14. Complexity of Class sset_next_month P1 tsnm b a c sset_next_day P2 e
class date {
public:
void set_next_month() {
if ( month == 12 ) { month = 1; year = year + 1; }
else { month = month + 1; } }
void set_next_day() {
if ( month == 1 || month == 3 || ... || month == 12 )
if ( day == 31 ) set_next_month();
else day = day + 1;
else
if ( day == 30 ) set_next_month();
private:
int year, month, day; };
sset_next_month P1
tsnm b a c
sset_next_day P2 e P3 g f P4 d1 d3 d2
SPLST 2005 Tartu, Estonia

15. Complexity of Class class date { public: void set_next_month() {
if ( month == 12 ) { month = 1; year = year + 1; }
else { month = month + 1; } }
void set_next_day() {
if ( month == 1 || month == 3 || ... || month == 12 )
if ( day == 31 ) set_next_month();
else day = day + 1;
else
if ( day == 30 ) set_next_month();
private:
int year, month, day; };
SPLST 2005 Tartu, Estonia

16. Our Measuring tool Supported languages Java 1.3 Java 1.4 (assert)
Future directions: Java 5 (generics) C# and C++
Implementation
ANTLR
User interface: standalone application and Eclipse Plug-in
Ouput
CSV
XML
SPLST 2005 Tartu, Estonia

17. Applied Metrics Object-Oriented Metrics Inner Class Depth
Inheritance level
Number of Children
Number of Methods
Number of Fields
LCOM
Henderson-Sellers LCOM*
Fan-out
SPLST 2005 Tartu, Estonia

18. Applied Metrics Size Metrics eLOC Number of Statements McCabe
Howatt-Baker
AV-graph
SPLST 2005 Tartu, Estonia

19. Test Data 367.000 eLOC 300.000 eLOC 5.000 eLOC 7.000 eLOC 900.000 eLOC
Java Standard Library
eLOC
jBOSS
eLOC
Omg.org.CORBA
5.000 eLOC
The measure tool (with mostly generated parser)
7.000 eLOC
Eclipse 3.0M6
eLOC
class – more than 1.5 million lines
SPLST 2005 Tartu, Estonia

20. Results
No statistical correlation between the OO and multi paradigm metrics:
OO metrics only measure the big picture
MPM considers more properties: higher density
The structural complexity of methods extremely increases the overall complexity
SPLST 2005 Tartu, Estonia

21. Conclusion
Multiparadigm programming requires software complexity measurement
Independent from paradigm-specific notions
Based on common features
Paradigm-specific features must/can be expressed by those common features
SPLST 2005 Tartu, Estonia