Clean Code - Design Patterns and Best Practices at Silicon Valley Code Camp

Clean Code I
Foothill College, Oct. 6th, 2013
Design Patterns
and Best Practices

Theo Jungeblut
• Engineering manager & lead by day
at AppDynamics in San Francisco
• Coder & software craftsman by night
• Architects decoupled solutions
tailored to business needs & crafts
maintainable code to last
• Worked in healthcare and factory
automation, building mission critical
applications, framework & platforms
• Degree in Software Engineering
and Network Communications
• Enjoys cycling, running and eating
theo@designitright.net
www.designitright.net

Rate Session & Win a Shirt
http://www.speakerrate.com/theoj

Where to get the Slides
http://www.slideshare.net/theojungeblut

Overview
• Why Clean Code
• Clean Code Developer Initiative
• Principles and Practices
• Code Comparison
• Q&A

Does writing Clean Code
make us more efficient?

The only valid Measurement of Code
Quality

Clean Code is maintainable
Source code must be:
• readable & well structured
• extensible
• testable

Software
Engineering
&
Software
Craftsmanship

The “Must Read”-Book(s)by Robert C Martin
A Handbook of Agile
Software
Craftsmanship
“Even bad code can
function. But if code
isn’t clean, it can bring a
development
organization to its
knees.”

Code Maintainability *
Principles Patterns Containers
Why? How? What?
Extensibility Clean Code Tool reuse
* from: Mark Seemann’s “Dependency Injection in .NET” presentation Bay.NET 05/2011

Clean Code Developer
Graphic by Michael Hönnig http://michael.hoennig.de/2009/08/08/clean-code-developer-ccd/

The 4 values of the CCD initiative
• Correctness
• Evolvability
• Production Efficiency
• Continuous Improvement
http://blogs.telerik.com/justteam/posts/13-05-16/clean-code-developer-school
by Ralf Westphal & Stefan Lieser – http://www.clean-code-developer.de

Clean Code Developer – 1st Iteration

KISS-Principle – “Keep It Simple Stupid”
http://blogs.smarter.com/blogs/Lego%20Brick.jpg
by Kelly Johnson

The Power of Simplicity
http://www.geekalerts.com/lego-iphone/
Graphic by Nathan Sawaya courtesy of brickartist.com

Chaos build from simplicity

Don’t repeat yourself (DRY)
by Andy Hunt and Dave Thomas in their book “The Pragmatic Programmer”
// Code Copy and Paste Method
public Class Person
{
public string FirstName { get; set;}
public string LastName { get; set;}
public Person(Person person)
{
this.FirstName = string.IsNullOrEmpty(person.FirstName)
? string.Empty : (string) person.FirstName.Clone();
this.LastName = string.IsNullOrEmpty(person.LastName)
? string.Empty : (string) person.LastName.Clone();
}
public object Clone()
{
return new Person(this);
}
}
// DRY Method
public Class Person
{
public string FirstName { get; set;}
public string LastName { get; set;}
public Person(Person person)
{
this.FirstName = person.FirstName.CloneSecured();
this.LastName = person.LastName.CloneSecured();
}
public object Clone()
{
return new Person(this);
}
}
public static class StringExtension
{
public static string CloneSecured(this string original)
{
return string.IsNullOrEmpty(original) ? string.Empty : (string)original.Clone();
}
}

Clean Code Developer – 2nd Iteration

Separation of Concerns
(SoC)
Single Responsibility
Principle
(SRP)

http://www.technicopedia.com/8865.html
The Product

http://www.technicopedia.com/8865.html
Component / Service

http://technicbricks.blogspot.com/2009/06/tbs-techpoll-12-results-2009-1st.html
Class, Struct, Enum etc.

Separation of Concerns (SoC)
• “In computer science,
separation of concerns (SoC) is
the process of separating a
computer program into distinct
features that overlap in
functionality as little as possible.
•A concern is any piece of
interest or focus in a program.
Typically, concerns are
synonymous with features or
behaviors. “
probably by Edsger W. Dijkstra in 1974
http://en.wikipedia.org/wiki/Separati
on_of_Concerns

Single Responsibility Principle (SRP)
“Every object should have a single responsibility, and that
responsibility should be entirely encapsulated by the class.”
by Robert C Martin
http://www.ericalbrecht.com
http://en.wikipedia.org/wiki/Single_responsibility_principle
public class Logger : ILogger
{
public Logger(ILoggingSink loggingSink)
{}
public void Log(string message)
{}
}

Clean Code Developer – 3rd Iteration

Information Hiding Principle
(IHP)

“.. information hiding is the principle of
segregation of the design decisions on a
computer program that are most likely to
change, ..”
Information Hiding Principle (IHP)
by David Parnas (1972)
http://en.wikipedia.org/wiki/Information_hiding

Interfaces / Contracts
public interface ILogger
{
void Log(string message);
}
• Decouple Usage and Implementation through introduction of a contract
• Allows to replace implementation without changing the consumer
public class Logger : ILogger
{
public Logger(ILoggingSink loggingSink)
{}
public void Log(string message)
{}
}

Liskov Substitution Principle
(LSP)

“Liskov’s notion of a behavioral subtype
defines a notion of substitutability for
mutable objects”
Liskov Substitution Principle (LSP)
by Barbara Liskov, Jannette Wing (1994)
http://en.wikipedia.org/wiki/Liskov_substitution_principle

Dependency Inversion Principle
(DIP)

Dependency Inversion Principle (DIP)
• “High-level modules should not depend on
low-level modules. Both should depend on
abstractions.
• Abstractions should not depend upon details.
Details should depend upon abstractions.”
http://en.wikipedia.org/wiki/Dependency_inversion_principle
by Robert C. Martin

Silicon Valley Code Camp Oct. ~ 5th – 6th
http://www.siliconvalley-codecamp.com

Mini Conferences – User Groups 

Clean Code Developer – 4th Iteration

An implementation is open for extension
but closed for modification
Open/Closed Principle (OCP)
by Bertrand Meyer (1988)
http://en.wikipedia.org/wiki/Open/closed_principle

“
• Each unit should have only limited knowledge
about other units: only units “closely” related
to the current unit.
• Each unit should only talk to its friends;
don’t talk to strangers
• Only talk to your immediate friends.”
Law of Demeter (LoD)
Northeastern University (1987)
http://en.wikipedia.org/wiki/Law_Of_Demeter

Single Responsibility Principle
Open/Closed Principle
Liskov Substitution Principle
Interface Segregation Principle
Dependency Inversion Principle
S
O
L
I
D
Robert C Martin: http://butunclebob.com/ArticleS.UncleBob.PrinciplesOfOod

Clean Code Developer – 5th Iteration

Summary Clean Code
Maintainability is achieved through:
• Readability (Coding Guidelines)
• Simplification and Specialization
(KISS, SoC, SRP, OCP, )
• Decoupling (LSP, DIP, IHP, Contracts,
LoD, CoP, IoC or SOA)
• Avoiding Code Bloat (DRY, YAGNI)
• Quality through Testability
(all of them!)

Downloads,
Feedback & Comments:
Q & A
theo@designitright.net
www.designitright.net
www.speakerrate.com/theoj

References…http://clean-code-developer.com
http://blogs.telerik.com/justteam/posts/13-05-16/clean-code-developer-school
http://michael.hoennig.de/2009/08/08/clean-code-developer-ccd/
http://butunclebob.com/ArticleS.UncleBob.PrinciplesOfOod
http://www.manning.com/seemann/
http://en.wikipedia.org/wiki/Keep_it_simple_stupid
http://picocontainer.org/patterns.html
http://en.wikipedia.org/wiki/Separation_of_concerns
http://en.wikipedia.org/wiki/Single_responsibility_principle
http://en.wikipedia.org/wiki/Information_hiding
http://en.wikipedia.org/wiki/Liskov_substitution_principle
http://en.wikipedia.org/wiki/Dependency_inversion_principle
http://stackoverflow.com/questions/6766056/dip-vs-di-vs-ioc
http://en.wikipedia.org/wiki/Open/closed_principle
http://en.wikipedia.org/wiki/Law_Of_Demeter
http://en.wikipedia.org/wiki/Don't_repeat_yourself
http://en.wikipedia.org/wiki/You_ain't_gonna_need_it
http://en.wikipedia.org/wiki/Component-oriented_programming
http://en.wikipedia.org/wiki/Service-oriented_architecture
http://www.martinfowler.com/articles/injection.html
http://www.codeproject.com/KB/aspnet/IOCDI.aspx
http://msdn.microsoft.com/en-us/magazine/cc163739.aspx
http://msdn.microsoft.com/en-us/library/ff650320.aspx
http://msdn.microsoft.com/en-us/library/aa973811.aspx
http://msdn.microsoft.com/en-us/library/ff647976.aspx
http://msdn.microsoft.com/en-us/library/cc707845.aspx
http://unity.codeplex.com/
http://www.idesign.net/idesign/DesktopDefault.aspx?tabindex=5&tabid=11

… more References
Resharper
http://www.jetbrains.com/resharper/
FxCop / Code Analysis
http://msdn.microsoft.com/en-us/library/bb429476(VS.80).aspx
http://blogs.msdn.com/b/codeanalysis/
http://www.binarycoder.net/fxcop/index.html
Code Contracts
http://msdn.microsoft.com/en-us/devlabs/dd491992
http://research.microsoft.com/en-us/projects/contracts/
StyleCop
http://stylecop.codeplex.com/
Ghostdoc
http://submain.com/products/ghostdoc.aspx
Spellchecker
http://visualstudiogallery.msdn.microsoft.com/
7c8341f1-ebac-40c8-92c2-476db8d523ce//
Lego (trademarked in capitals as LEGO)

Blog, Rating, Slides
http://www.DesignItRight.net
www.slideshare.net/theojungeblut

Time to say Thank You!
The Organizers
Foothill College (team)
The volunteers (how about you?)
TheSponsors

… thanks for you attention!
And visit and support the
www.siliconvalley-codecamp.com
Please fill out the
feedback, and…

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