All 3 Clean Code presentations provide great value by themselves, but taken together are designed to offer a holistic approach to successful software creation. This first session creates the foundation for the 2nd and 3rd Clean Code presentation on Dependency Injection, as it explains expected base knowledge. Why writing Clean Code makes us more efficient Over the lifetime of a product, maintaining the product is actually one - if not the most - expensive area(s) of the overall product costs.
Writing clean code can significantly lower these costs. However, writing clean code also makes you more efficient during the initial development time and results in more stable code. You will be presented design patterns and best practices which will make you write better and more easily maintainable code, seeing code in a holistic way.
You will learn how to apply them by using an existing implementation as the starting point of the presentation. Finally, patterns & practices benefits are explained. This presentation is based on C# and Visual Studio 2012. However, the demonstrated patterns and practice can be applied to every other programming language too.
Note: Moving forwards this presentation will be updated with the latest version of the slides for the last event I did the presentation instead of creating new separate slide decks here on SlideShare.
Presentation dates and locations:
2015-10-03 Silicon Valley Code Camp, San Jose, CA
2015-06-27 SoCal Code Camp - San Diego, CA
2014-11-14 SoCal Code Camp - Los Angeles, CA
2014-10-18 Desert Code Camp - Chandler, AZ
2014-10-11 Silicon Valley Code Camp, Los Altos Hills, CA
2. Theo Jungeblut
• Director Customer Success at
AppDynamics in San Francisco
• Coder & software craftsman by night,
first time dad and house builder
• Architects decoupled solutions
& 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
12. 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.”
15. 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
16. Graphic by Michael Hönnig http://michael.hoennig.de/2009/08/08/clean-code-developer-ccd/
Clean Code Developer – 1st Iteration
by Ralf Westphal & Stefan Lieser – http://www.clean-code-developer.de
18. KISS-Principle – “Keep It Simple Stupid”
http://blogs.smarter.com/blogs/Lego%20Brick.jpg
by Kelly Johnson
19. The Power of Simplicity
http://www.geekalerts.com/lego-iphone/
Graphic by Nathan Sawaya courtesy of brickartist.com
Graphic by Nathan Sawaya courtesy of brickartist.com
20. Chaos build from simplicity
Graphic by Nathan Sawaya courtesy of brickartist.com
22. 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.Copy(person.FirstName);
this.LastName = string.IsNullOrEmpty(person.LastName)
? string.Empty : string.Copy(person.LastName);
}
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.Copy(original);
}
}
23. Graphic by Michael Hönnig http://michael.hoennig.de/2009/08/08/clean-code-developer-ccd/
Clean Code Developer – 1st Iteration
by Ralf Westphal & Stefan Lieser – http://www.clean-code-developer.de
24. Clean Code Developer – 2nd Iteration
by Ralf Westphal & Stefan Lieser – http://www.clean-code-developer.de
Graphic by Michael Hönnig http://michael.hoennig.de/2009/08/08/clean-code-developer-ccd/
29. 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/Separation_of_Concerns
30. 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)
{}
}
32. Clean Code Developer – 2nd Iteration
by Ralf Westphal & Stefan Lieser – http://www.clean-code-developer.de
Graphic by Michael Hönnig http://michael.hoennig.de/2009/08/08/clean-code-developer-ccd/
33. Graphic by Michael Hönnig http://michael.hoennig.de/2009/08/08/clean-code-developer-ccd/
Clean Code Developer – 3rd Iteration
by Ralf Westphal & Stefan Lieser – http://www.clean-code-developer.de
35. “.. 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
36. 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)
{}
}
38. “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
http://www.objectmentor.com/resources/articles/lsp.pdf
40. 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
http://www.objectmentor.com/resources/articles/dip.pdf
by Robert C. Martin
41. Next Silicon Valley Code Camp Oct. 2016
https://www.siliconvalley-codecamp.com
43. Graphic by Michael Hönnig http://michael.hoennig.de/2009/08/08/clean-code-developer-ccd/
Clean Code Developer – 3rd Iteration
by Ralf Westphal & Stefan Lieser – http://www.clean-code-developer.de
44. Graphic by Michael Hönnig http://michael.hoennig.de/2009/08/08/clean-code-developer-ccd/
Clean Code Developer – 4th Iteration
by Ralf Westphal & Stefan Lieser – http://www.clean-code-developer.de
46. 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
48. “
• 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
49. 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
50. Graphic by Michael Hönnig http://michael.hoennig.de/2009/08/08/clean-code-developer-ccd/
Clean Code Developer – 4th Iteration
by Ralf Westphal & Stefan Lieser – http://www.clean-code-developer.de
51. Graphic by Michael Hönnig http://michael.hoennig.de/2009/08/08/clean-code-developer-ccd/
Clean Code Developer – 5th Iteration
by Ralf Westphal & Stefan Lieser – http://www.clean-code-developer.de
53. 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!)
54. Downloads,
Feedback & Comments:
Q & A
Graphic by Nathan Sawaya courtesy of brickartist.com
theo@designitright.net
www.designitright.net
http://speakerrate.com/ speakers
/18667-theo-jungeblut
55. Time to say Thank You!
The Organizers
Evergreen Valley College (team)
The volunteers (how about you?)
TheSponsors
Picturesfromhttp://blog.siliconvalley-codecamp.com