R E A D C L E A N C O D E : A H A N D B O O K O F S O F T W A R E C R A F T S M A N S H I P. C H A P T E R S 2 A N D 4.

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1 R E A D C L E A N C O D E : A H A N D B O O K O F S O F T W A R E C R A F T S M A N S H I P. C H A P T E R S 2 A N D 4. H T T P S : / / R E F A C T O R I N G. G U R U / R E F A C T O R I N G / C A T A L O G

2 WHAT IS CLEAN CODE? 2

3 WHAT IS CLEAN CODE? 3

4 WHAT IS CLEAN CODE? 4

5 HOW TO WRITE CLEAN CODE Read clean code. Read your own code. Coding is an iterative process Write Make it work Make it work right Refactoring 5

6 CODE REFACTORING the process of restructuring existing computer code without changing its external behavior. Excessively long methods Split temporary variables Remove assignments to parameters double temp = 2 * (height + width); System.out.println(temp); temp = height * width; System.out.println(temp); final double perimeter = 2 * (height + width); System.out.println(perimeter); final double area = height * width; System.out.println(area); 6

7 CLASS REFACTORING Moving methods Hide delegate Extracting classes Remove middleman 7

8 GENERALIZATION REFACTORING Pull up a field / method/ constructor body Push down a field/ method / constructor body Extract subclasses / superclass / interface 8

9 METHOD REFACTORING void printowing() { printbanner(); printdetails(getoutstanding()); } void printdetails(double outstanding) { System.out.println("name: " + name); System.out.println("amount: " + outstanding); } void printowing() { printbanner(); //print details System.out.println("name: " + name); System.out.println("amount: " + getoutstanding()); } double temp = 2 * (height + width); System.out.println(temp); temp = height * width; System.out.println(temp); final double perimeter = 2 * (height + width); System.out.println(perimeter); final double area = height * width; System.out.println(area); 9

10 METHOD REFACTORING int discount(int inputval, int quantity) { if (inputval > 50) { inputval -= 2; } //... } int discount(int inputval, int quantity) { int result = inputval; if (inputval > 50) { result -= 2; } //... } 10

11 METHOD REFACTORING Replace methods with method objects. 11

12 WHAT IS IN A NAME? The name of a variable, function, or class, should answer all the big questions. It should tell you why it exists, what it does, and how it is used. If a name requires a comment, then the name does not reveal its intent. 12

13 NAMING Use intention-revealing names Avoid disinformation Make meaningful distinctions Use pronounceable names Use searchable names 13

14 NAMING CONVENTIONS CamelOrUnder_score? itdependsonwhich_you_find_easier_to_readorwrite! nomatterwhichyouprefer_don t_mix! Variation of camelcase is PascalCase 14

15 NAMING Encodings A prefix or a postfix for a variable name that indicates its type What happens when an object changes types (downcasting)? How many changes you have to make when you change a varriable s data type? Hungarian: Common encodings Not Okay to do: Class members are prefixed with m_ Okay to do : Interfaces are preceded with IShapeFactory, realized by class ShapeFactory Okay: Capitalize the first letter in a constructor name in Javascript. 15

16 COMMENTS The best comment : Is a comment that you did not have to write! Using the programming language constructs to express program logic Under all other circumstances, comment your code! 16

17 COMMENTS Legal comments: copyright and authorship statements Informative comments Explanation of intent 17

18 INLINE COMMENTS Clarification TODO comments 18

19 BLOCK COMMENTS 19

20 JAVA DOC DOCUMENTATION 20

21 COMMENTS NOT TO DO 21

22 SOFTWARE LICENSE MODELS Free Software Foundation Grant users the freedom to use, study, distribute and modify code freely. Richard Stallman (RMS) founded the free software foundation in 1983/5. Initially concerned with the development and evolution of free software (such as GNU), it now focuses on issues of intellectual property for free content. 22

23 SOFTWARE LICENSE MODELS- COPY LEFT Copyleft vs. Copyrights Use existing copyright laws to ensure a creative work (software- art ) remains freely available. Derivative work can only be distributed under the same license terms. Essential motivation for the contributors of open software. Reciprocity share-alike requirements ( give everyone the same rights you were granted). GPL ( GNU General Public License) The first copyleft licence Linux kernel, GNU Compiler Collection (GCC) LGPL (Lesser General Public License) LGPL software (for example libraries) can be linked to proprietary software without releasing its source. 23

24 SOFTWARE LICENSE MODELS PERMISSIVE FREE SOFTWARE LICENSES Berkeley Software Distribution (BSD)-like licenses Code can be turned to proprietary software Retain the copyright notice Author names of original software are not endorsement. 24

25 RECENT DEVELOPMENT SaaS: Software as a service License model via subscription PaaS: Platform as a service Minimum configuration Provides platform services such.net, Java runtime etc, database, for example Mongo IaaS: Infrastructure as a service 25