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Writing High Quality Code

Agile 2012

DB20111207www.techniquesofdesign.cominfo@techniquesofdesign.com COPYRIGHT © TECHNIQUES OF DESIGN

www.ToBeAgile.cominfo@ToBeAgile.com

© Copyright 2009-2012 To Be Agile DB20120717

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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

Type Coupling

Interface Coupling

Abstract 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