A controlled experiment on inheritance depth as a cost factor for code maintenance

Prechelt, Lutz; Unger, Barbara; Philippsen, Michæl; Tichy, Walter F.

doi:10.1016/s0164-1212(02)00053-5

Cited by 47 publications

(23 citation statements)

References 9 publications

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“…suggested that inheritance should be used with care and only when needed. In two controlled experiments, Prechelt et al, (2003) reported that maintenance effort was positively associated with inheritance depth. In terms of further empirical studies into inheritance, Chidamber et al, (1998) empirically studied three commercial OO systems none of which showed significant use of inheritance.…”

Section: Motivation and Related Workmentioning

confidence: 99%

Class movement and re-location: An empirical study of Java inheritance evolution

Nasseri¹,

Counsell²,

Shepperd³

2010

Journal of Systems and Software

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Inheritance is a fundamental feature of the Object-Oriented (OO) paradigm. It is used to promote extensibility and reuse in OO systems. Understanding how systems evolve, and specifically, trends in the movement and re-location of classes in OO hierarchies can help us understand and predict future maintenance effort. In this paper, we explore how and where new classes were added as well as where existing classes were deleted or moved across inheritance hierarchies from multiple versions of four Java systems. We observed first, that in one of the studied systems the same set of classes was continuously moved across the inheritance hierarchy. Second, in the same system, the most frequent changes were restricted to just one sub-part of the overall system. Third, that a maximum of three levels may be a threshold when using inheritance in a system; beyond this level very little activity was observed, supporting earlier theories that, beyond three levels, complexity becomes overwhelming. We also found evidence of 'collapsing' hierarchies to bring classes up to shallower levels. Finally, we found that larger classes and highly coupled classes were more frequently moved than smaller and less coupled classes. Statistical evidence supported the view that larger classes and highly coupled classes were less cohesive than smaller classes and lowly coupled classes and were thus more suitable candidates for being moved (within an hierarchy).

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Section: Motivation and Related Workmentioning

confidence: 99%

Class movement and re-location: An empirical study of Java inheritance evolution

Nasseri¹,

Counsell²,

Shepperd³

2010

Journal of Systems and Software

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“…The multi-method study of Wood et al, [25] suggests that inheritance should be used with care and only when needed. Finally, two controlled experiments by Prechelt et al [24] found that it took longer to maintain a program with higher levels of inheritance than a program containing fewer inheritance features.…”

Section: Related Workmentioning

confidence: 99%

An Empirical Study of Evolution of Inheritance in Java OSS

Nasseri¹,

Counsell²,

Shepperd³

2008

19th Australian Conference on Software Engineering (Aswec 2008)

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Previous studies of Object-Oriented (OO) software have reported avoidance of the inheritance mechanism and cast doubt on the wisdom of 'deep' inheritance levels. From an evolutionary perspective, the picture is unclear -we still know relatively little about how, over time, changes tend to be applied by developers. Our conjecture is that an inheritance hierarchy will tend to grow 'breadth-wise' rather than 'depth-wise'. This claim is made on the basis that developers will avoid extending depth in favour of breadth because of the inherent complexity of having to understand the functionality of superclasses. Thus the goal of our study is to investigate this empirically. We conduct an empirical study of seven Java Open-Source Systems (OSSs) over a series of releases to observe the nature and location of changes within the inheritance hierarchies. Results show a strong tendency for classes to be added at levels one and two of the hierarchy (rather than anywhere else). Over 96% of classes added over the course of the versions of all systems were at level 1 or level 2. The results suggest that changes cluster in the shallow levels of a hierarchy; this is relevant for developers since it indicates where remedial activities such as refactoring should be focused.

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“…Statistically significant results suggested that a class located deep in the inheritance hierarchy (given by its DIT) was more faultprone than a class higher up in the hierarchy; the study suggested that extensive use of inheritance could have had the opposite effect to that of aiding the maintenance process. Prechelt et al [Prechelt03] suggest that maintenance effort is positively associated with inheritance depth (i.e., the deeper the inheritance hierarchy, the more maintenance effort required -and this would suggest that this is where the potential for faults to be invested lay). Wood et al [Wood99] advise that inheritance should be used with care and only when needed.…”

Section: Motivation and Related Workmentioning

confidence: 99%

“…The extent to which these benefits can be realized is an issue of significant interest for exploratory, empirical software engineering studies. A number of studies have also cast doubt on the extent to which deep levels of inheritance assist with the maintainability of a system [Prechelt03,Cartwright00,Harrison97,Basili96].…”

Section: Introductionmentioning

confidence: 99%

Size, Inheritance, Change and Fault-proneness in C# software.

Gatrell¹,

Counsell²

2010

JOT

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P u b l i s h e d b y E T H Z u r i c h , C h a i r o f S o f t w a r e E n g i n e e r i n g © J o t , 2 0 1 0 O n l i n e a t h t t p : / / w w w . Abstract This paper documents a study of change in commercial, proprietary C# software and attempts to determine whether a relationship exists between class changes and faults and the design context of a class, namely its size and inheritance relationships.Results showed a strong positive correlation between the size of a class and change-proneness but not for all the class features studied. Classes within a specific range of a) inheritance depth and b) number of children were found to be relatively more prone to change. For the fault data and for the same class features, similar results were found. The most striking result to emerge however was the existence of an inheritance depth 'interval' between which change (and faultproneness) were at their highest. Below and above that interval, both features were less prominent. The results thus add weight to the claims of other previous studies which suggest that there is an optimal level of inheritance, beyond which maintenance may become problematic from both a change and fault perspective.

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A controlled experiment on inheritance depth as a cost factor for code maintenance

Cited by 47 publications

References 9 publications

Class movement and re-location: An empirical study of Java inheritance evolution

Class movement and re-location: An empirical study of Java inheritance evolution

An Empirical Study of Evolution of Inheritance in Java OSS

Size, Inheritance, Change and Fault-proneness in C# software.

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