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Writing High Quality Code
Agile 2012
www.ToBeAgile.com
© Copyright 2009-2012 To Be Agile DB20120717
info@ToBeAgile.com
www.techniquesofdesign.com
info@techniquesofdesign.com COPYRIGHT © TECHNIQUES OF DESIGN DB20111207
Thank you for being here
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I am David Bernstein
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Standing on the shoulders of giants
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What is quality?
Service Products
?
Software
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What makes software good?
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Correctness is not enough
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Remember when?
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Things change
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Dealing with change
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What makes code easy to change?
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What makes code difficult to change?
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Code pathologies
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Rigidity – hard to repurpose
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Viscosity – difficult to change
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Complexity – unsure how to change
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Opaque – difficult to understand
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Brittleness – expensive to change
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Pathologies scare us
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It’s harder on larger projects
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Quality in software
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6 software qualities
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Cohesive
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Language and software
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Class cohesion
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Method cohesion
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Pathologies of poor cohesion
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Non-redundant
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Finding redundancy
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Types of redundancy
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Can non-identical code be redundant?
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Can identical code be non-redundant?
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Redundant intent
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Code investment or debt
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Pathologies of redundancy
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Encapsulated
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What can be encapsulated?
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What you don’t know…
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…can’t hurt you
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Encapsulate by policy
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Optimization
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Can you encapsulate it?
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Many ways to encapsulate
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Pathologies of poor encapsulation
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Assertive
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Assertive or inquisitive?
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Object therapy
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“With great state comes great responsibility”
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Winston Churchill, Spiderman’s Uncle
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Pathologies of inquisitiveness
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Testable
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Testability guides design
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Pathologies of poor testability
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Explicit
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Good and bad coupling
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Bad coupling
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Coupling
Type
Interface
Abstract
Concrete
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Coupling example
Abstract Coupling
Type Coupling
Interface Coupling
No Concrete Coupling
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Pathologies of bad coupling
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The six code qualities…
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– Cohesive
– non-Redundant
– Encapsulated
– Assertive
– Testable
– Explicit
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…spells CREATE
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Code qualities guide us
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Thank You!
We have just scratched the surface, to learn more:
– Read my blog: http://ToBeAgile.com/blog
– Follow me on Twitter (@ToBeAgile)
– Attend my one of my Certified Scrum Developer trainings
Public Certified Scrum Developer Essentials classes:
– October 15 – 19, 2012 in Redwood City, CA
Public Agile Software Developer Essentials classes:
– December 10 – 14, 2012 Online (8:00 am-12:00 pm PT)
Private classes available for groups of 8 or more developers
– Learn more at http://ToBeAgile.com
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