How to Apply Design Principles in Practice
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The document discusses the application of design principles in software development, emphasizing the importance of a well-educated mindset in design over specific technologies. It covers the SOLID principles, practical applications through examples, and techniques for recognizing and refactoring 'design smells' to improve code quality. Key takeaways include the proactive use of enabling techniques, refactoring, and employing design analysis tools.
![Refactored example …
You can use only date,
time, or even timezone,
and combine them as
needed!
LocalDate today = LocalDate.now();
System.out.println(today);
LocalTime now = LocalTime.now();
System.out.println(now);
ZoneId id = ZoneId.of("Asia/Tokyo");
System.out.println(id);
LocalDateTime todayAndNow = LocalDateTime.now();
System.out.println(todayAndNow);
ZonedDateTime todayAndNowInTokyo = ZonedDateTime.now(ZoneId.of("Asia/Tokyo"));
System.out.println(todayAndNowInTokyo);
2016-03-17
13:28:06.927
Asia/Tokyo
2016-03-17T13:28:06.928
2016-03-17T16:58:06.929+09:00[Asia/Tokyo]](https://image.slidesharecdn.com/howtoapplydesignprinciplesinpractice-160616124317/85/How-to-Apply-Design-Principles-in-Practice-21-320.jpg)
![What’s that smell?
switch'(transferType)'{'
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pixel'='bdata[0]'&'0xff;'
length'='bdata.length;'
break;'
case'DataBuffer.TYPE_USHORT:'
short'sdata[]'='(short[])inData;'
pixel'='sdata[0]'&'0xffff;'
length'='sdata.length;'
break;'
case'DataBuffer.TYPE_INT:'
int'idata[]'='(int[])inData;'
pixel'='idata[0];'
length'='idata.length;'
break;'
default:'
throw' new' UnsupportedOperaQonExcepQon("This' method' has' not' been' "+' "implemented'
for'transferType'"'+'transferType);'
}'](https://image.slidesharecdn.com/howtoapplydesignprinciplesinpractice-160616124317/85/How-to-Apply-Design-Principles-in-Practice-23-320.jpg)
inData;(
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length(=(bdata.length;(
break;(
case(DataBuffer.TYPE_USHORT:(
short(sdata[](=((short[])inData;(
pixel(=(sdata[0](&(0xffff;(
length(=(sdata.length;(
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case(DataBuffer.TYPE_INT:(
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throw( new( UnsupportedOperaRonExcepRon("This( method(
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}!](https://image.slidesharecdn.com/howtoapplydesignprinciplesinpractice-160616124317/85/How-to-Apply-Design-Principles-in-Practice-24-320.jpg)
How to Apply Design Principles in Practice
- 1. How to Apply Design Principles in Practice? Ganesh Samarthyam Entrepreneur; Author; Conf. speaker [email protected] www.designsmells.com; www.codeops.tech
- 2. "The critical design tool for software development is a mind well educated in design principles. It is not the UML or any other technology" - Craig Larman
- 3. Why care about design quality and design principles?
- 4. "We thought we were just programming on an airplane” - Kent Beck
- 5. SOLID principles • There&should&never&be&more&than&one&reason&for&a&class&to& change&& Single'Responsibility' Principle'(SRP)' • So6ware&en88es&(classes,&modules,&func8ons,&etc.)&should& be&open&for&extension,&but&closed&for&modifica8on& Open'Closed'Principle' (OCP)' • Pointers&or&references&to&base&classes&must&be&able&to&use& objects&of&derived&classes&without&knowing&it& Liskov’s'Subs<tu<on' Principle'(LSP)' • Depend&on&abstrac8ons,¬&on&concre8ons& Dependency'Inversion' Principle'(DIP)' • Many&clientGspecific&interfaces&are&beHer&than&one& generalGpurpose&interface& Interface'Segrega<on' Principle'(ISP)'
- 7. How to apply principles in practice? Principles Code How to bridge the gap?
- 8. Proactive application: enabling techniques
- 12. Principle of Least Astonishment: Example
- 14. Use “enabling techniques” to apply design principles in practice Key-takeaway #1
- 16. Discussion example // using java.util.Date Date today = new Date(); System.out.println(today); $ java DateUse Wed Dec 02 17:17:08 IST 2015 Why should we get the time and timezone details if I only want a date? Can I get rid of these parts? No!
- 17. “So what”! Date today = new Date(); System.out.println(today); Date todayAgain = new Date(); System.out.println(todayAgain); System.out.println(today.compareTo(todayAgain) == 0); Thu Mar 17 13:21:55 IST 2016 Thu Mar 17 13:21:55 IST 2016 false What is going on here?
- 18. Refactoring for Date Replace inheritance with delegation
- 20. Refactored solution LocalDate today = LocalDate.now(); System.out.println(today); LocalDate todayAgain = LocalDate.now(); System.out.println(todayAgain); System.out.println(today.compareTo(todayAgain) == 0); 2016-03-17 2016-03-17 true Works fine now!
- 21. Refactored example … You can use only date, time, or even timezone, and combine them as needed! LocalDate today = LocalDate.now(); System.out.println(today); LocalTime now = LocalTime.now(); System.out.println(now); ZoneId id = ZoneId.of("Asia/Tokyo"); System.out.println(id); LocalDateTime todayAndNow = LocalDateTime.now(); System.out.println(todayAndNow); ZonedDateTime todayAndNowInTokyo = ZonedDateTime.now(ZoneId.of("Asia/Tokyo")); System.out.println(todayAndNowInTokyo); 2016-03-17 13:28:06.927 Asia/Tokyo 2016-03-17T13:28:06.928 2016-03-17T16:58:06.929+09:00[Asia/Tokyo]
- 22. More classes in Date/Time API
- 23. What’s that smell? switch'(transferType)'{' case'DataBuffer.TYPE_BYTE:' byte'bdata[]'='(byte[])inData;' pixel'='bdata[0]'&'0xff;' length'='bdata.length;' break;' case'DataBuffer.TYPE_USHORT:' short'sdata[]'='(short[])inData;' pixel'='sdata[0]'&'0xffff;' length'='sdata.length;' break;' case'DataBuffer.TYPE_INT:' int'idata[]'='(int[])inData;' pixel'='idata[0];' length'='idata.length;' break;' default:' throw' new' UnsupportedOperaQonExcepQon("This' method' has' not' been' "+' "implemented' for'transferType'"'+'transferType);' }'
- 24. Don’t repeat yourself (DRY) principle protected(int(transferType;! protected(DataBuffer(dataBuffer;! pixel(=(dataBuffer.getPixel();( length(=(dataBuffer.getSize();! switch((transferType)({( case(DataBuffer.TYPE_BYTE:( byte(bdata[](=((byte[])inData;( pixel(=(bdata[0](&(0xff;( length(=(bdata.length;( break;( case(DataBuffer.TYPE_USHORT:( short(sdata[](=((short[])inData;( pixel(=(sdata[0](&(0xffff;( length(=(sdata.length;( break;( case(DataBuffer.TYPE_INT:( int(idata[](=((int[])inData;( pixel(=(idata[0];( length(=(idata.length;( break;( default:( throw( new( UnsupportedOperaRonExcepRon("This( method( has( not( been( "+( "implemented( for( transferType( "( +( transferType);( }!
- 25. Refactor “bad smells” to apply design principles in practice Key-takeaway #2
- 26. Tool driven approach for design quality
- 29. Comprehension tools Imagix 4D http://www.imagix.com
- 30. Critique, code-clone detectors, and metric tools Infusion www.intooitus.com/products/infusion
- 31. Critique, code-clone detectors, and metric tools Designite www.designite-tools.com
- 32. Critique, code-clone detectors, and metric tools PMD Copy Paste Detector (CPD) http://pmd.sourceforge.net/pmd-4.3.0/cpd.html
- 33. Critique, code-clone detectors, and metric tools Understand https://scitools.com
- 34. Technical debt quantification/visualization tools Sonarqube http://www.sonarqube.org
- 36. Use design analysis tools to apply design principles in practice Key-takeaway #3
- 37. Key take-aways ❖ Thee effective ways to apply design principles in practice: ❖ Use “enabling techniques” ❖ Refactoring “bad smells” ❖ Use design analysis tools
- 38. Proactive application: enabling techniques
- 39. Reactive application: refactoring smells
- 40. Enablers: tools for refactoring Jhawk& (Java)& CodeCity&& (C++,&Java,&C#)&& CppDepend& (C++)& Sotograph& (C++,&Java,&C#)& Imagix&4D&& (C,&C++,&Java)& La?x& (C/C++,&Java,&C#)&& SolidSX&& (C++,&Java,&C#)& Bauhaus& (C/C++,&Java,&C#)& Structure101&& (Java,&C#)& Understand&& (C/C++,&Java,&C#)& Simian& (C/C++,&Java,&C#,&…)& Jarchitect& (Java)& Ndepend& (C#)& Stan4J& (Java)& InFusion& (C/C++,&Java)& InCode& (C/C++,&Java)&
- 41. Our upcoming workshops Modern Software Architecture - July 2 Modern Programming with Java 8 - July 16 Software Refactoring in Practice - July 23