Code Metrics & Design Patterns

Measuring the effects of Design Patterns

David KempMelbourne Patterns, March 2007

David Kemp: March 2007 Code Metrics & Design Patterns 2

Code Metrics & Design Patterns

What are code metrics?Example metrics.Limitations.Examples of measuring before & after

refactoring to a pattern.Metrics tools.References

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Code Metrics

Measuring software:SizeComplexityCoupling and cohesion

(Not to be confused with project metrics)

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Examples

Fanout% Code duplication…

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Limitations

Not all aspects of design are measurableOpinions differ on “good design”Unintended effects of measuring

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Code Metrics & Design Patterns

Examples taken from:

Brian Huston,The effects of design pattern applicationon metric scores.The Journal of Systems and Software, 2001.

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Mediator

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Bridge

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Visitor

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Stack Before Refactoring

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Stack After Refactoring

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References & Resources

Books & Articles: Brian Huston,The effects of design pattern application on metric scores.

The Journal of Systems and Software, 2001. Michele Lanza, Radu Marinescu, Object-Oriented Metrics in Practice

Tools: Eclipse Metrics (http://www.eclipseplugincentral.com/) Complexian (http://www.martyandrews.net/resources/complexian.html) Simian (http://www.redhillconsulting.com.au/products/simian/) IPlasma (http://loose.upt.ro/iplasma/). JHawk (http://www.virtualmachinery.com/jhawkprod.htm) Checkstyle (http://checkstyle.sourceforge.net/)