David Gómez G. @dgomezg

Measuring Code Quality: WTF/min Code from the real world that could give you a stroke and some advices to not replicate them.

Measuring Code Quality: WTF/min

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@dgomezg

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Quality CODE RELATED CONCEPTS

http://www.osnews.com/story/19266/WTFs_m

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@dgomezg

Measuring Code Quality: WTF/min

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A surface indication that usually

corresponds to a deeper problem in the

system

Term coined by Kent Beck

CODE SMELL

@dgomezg

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You write code for a computer to read

Some Misconceptions

You write code to be read by a developer maintaining your code. The computer reads the compiled code

Writing smart code, you will improve performance

Developers spend most of the time writing code

Developers spend most of time reading code

@dgomezg

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Examples of real code from the real world

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The following code has been modified slightly

to protect anonymity of authors

!

but always respect the original idea (although it could be difficult to believe)

/*        */10

Comments are useful, butCOMMENTS

Only if they add information

or if they explain the code

Don’t describe what the code is doing

Explain why (pre/post-conditions)

Use cases (for methods/types/functions)

/*        */COMMENTS: Unuseful info

@dgomezg

/*        */COMMENTS: Unuseful info

/** * Método get Disponibilidad. * * @return Returns the disponibilidad. */ public String getDisponibilidad() { // We will get back to the implementation detail // More fun later }

@dgomezg

/*        */COMMENTS: Unuseful info   /**  Atributo  codCircuito.  */     private  String  codCircuito;  !   /**      *  Método  get  codCircuito.      *        *  @return  String      */     public  String  getCodCircuito()  {       return  codCircuito;     }  

@dgomezg

/*        */COMMENTS:

Remember to sign your code////////////////////////Manuela  Logger  log  =  LoggerFactory.getLogger(MyClass.class.getName());  ////////////////////////

@dgomezg

/*        */COMMENTS:

A good marketing tool/** * This method removes all selected files * * Returns a jQuery collection of all affected elements. * * @name reset * @type jQuery * @author Daniel B. ( http://www.visit-my-web.com/) * */ reset: function(){

@dgomezg

/*        */COMMENTS:

FOOL THE code READEr Producto p = null; List prod = null; List listaElementos = new ArrayList(); // if (nElements > 80) { cmd.setOrden(Producto.SELECT_POR_TIPO); l = new ListParam(); l.add(new Integer(idTipoProducto)); l.add(new Integer(idCategoria));

* for the trick to work out, keep the indentation@dgomezg

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Exceptions are just that: ExceptionsExceptions

Catch only if you can handle it

Declare the exact type

Don’t use for: Flow Control

State demarcation (other than Error)

Exceptions: Simply retrowingpublic  static  Class  cargaClase(java.lang.String  pnombreClase)                  throws  ClassNotFoundException  {          ClassLoader  oloader  =  new  ClasesUtil().getClass()  

.getClassLoader();          try  {                  return  oloader  !=  null  ?                       oloader.loadClass(pnombreClase)                       :  Class.forName(pnombreClase);  

       }  catch  (ClassNotFoundException  x)  {                                        throw  x;          }  }

@dgomezg

Exceptions: NPE PARANOIA

  while  (session  !=  null)  {       numSessions++  ;       if  (session  !=  null)  {       ...  }  ...  

}    

It’s better to check twice to avoid a NullPointerException

@dgomezg

while (session != null) { numSessions++ ; if (session != null) { //.... } else { log.warn("Null session detected.” +

“ Starting session Synchronization"); //.... dead code follows... } }

Exceptions: NPE PARANOIAIt’s better to check twice to avoid a NullPointerException

extra points if you add ‘dead code’ to the else block

@dgomezg

Exceptions: Flow Controlpublic  class  ProcesoTerminadoCorrectamenteException                            extends  Exception  {  !}  

Man! When a process which right ends is an exception… That’s a good confidence in your system!

@dgomezg

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NAMINGUse descriptive names

Describe what a Class/function/method does, not what it means Describe what a variable/attribute holdsDon’t use abbreviations

Code for readability

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NAMING: What does this method do?        if(  p  !=  null){                  applyBusinessLogic(p,estado,manager);          }

  public  void  onButtonPressed(ActionEvent  e)  {       FormData  formData  =  parseFromEvent(e);       theAlgorithm(formData);     }  

@dgomezg

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UnNecessary code

Developers should be lazy

Don’t write code you don’t need

Don’t repeat yourself

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UnNecessary code: Wrapping well-known APIs

public  static  String  substringBefore(String  str,String  separator)  {          return  (org.apache.commons.lang.StringUtils  

.substringBefore(str,  separator));  }  

@dgomezg

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UnNecessary code: Wrapping well-known APIs

  public  String  getPropiedad(String  clave)  {       return  wrappedCacheAdmin.getProperty(clave);     }         public  void  setClaseAlgoritmo(String  clase)  {       wrappedCacheAdmin.setAlgorithmClass(clase);     }  

@dgomezg

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UnNecessary code: Clever? Code        /**  La  constante  CERO.  */          public  static  final  int  CERO=0;                    /**  La  constante  UNO.  */          public  static  final  int  UNO=1;                    /**  La  constante  DOS.  */          public  static  final  int  DOS=2;                    /**  La  constante  TRES.  */          public  static  final  int  TRES=3;  

@dgomezg

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UnNecessary code: Clever? CodeChallenge: Could you tell what will print the following code?

    System.out.println(DOS  *  TRES);

@dgomezg

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2K Effect… We miss you!

NODO 4 !!# Planificacion Procesos Batch # (Formato ss mm hh dd MM yyyy) # cron.sync=0 00 12 * * ? cron.download=0 00 12 * * 2030 cron.reports=0 00 12 * * 2030

NODO 3 !# Planificacion Procesos Batch # (Formato ss mm hh dd MM yyyy) # cron.sync=0 00 16 * * ? cron.download=0 00 03 * * ? 2030 cron.reports=0 00 03 * * ? 2030

NODO 1 !# Planificacion Procesos Batch # (Formato ss mm hh dd MM yyyy) # cron.sync=0 00 15 * * ? cron.download=0 00 23 * * ? 2030 cron.reports=0 00 23 * * ? 2030

@dgomezg

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UnNecessary code: SOP

/** * Método get Disponibilidad. * * @return Returns the disponibilidad. */ public String getDisponibilidad() { if (numeroPuestos == 0) return "No"; else return "Si"; }

Introducing SOP: String Oriented Programming

@dgomezg

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UnNecessary code: TAKING ADVICE TOO SERIOUSLY

String concatenation in Java is not recommended. Use StringBuffer or StringBuilder insteadStringBuffer hql = new StringBuffer("select distinct config from Config config ");

Query query = session.createQuery(hql.toString()) ;

Don’t push the recommendations to the limits!!!@dgomezg

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UnNecessary code: The indentation MADNESS

                                 }                               });                             }                           }                       });                        }                   });                 }               }             ]           }         },            ]     });  });  

@dgomezg

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UnNecessary code: PROTECT YOUR CODE

static  OSStatus  SSLVerifySignedServerKeyExchange(SSLContext  *ctx,  bool  isRsa,  SSLBuffer  signedParams,                                              uint8_t  *signature,  UInt16  signatureLen)  {     OSStatus                err;     ...  !   if  ((err  =  SSLHashSHA1.update(&hashCtx,  &serverRandom))  !=  0)       goto  fail;     if  ((err  =  SSLHashSHA1.update(&hashCtx,  &signedParams))  !=  0)       goto  fail;       goto  fail;     if  ((err  =  SSLHashSHA1.final(&hashCtx,  &hashOut))  !=  0)       goto  fail;     ...  }  //  https://www.imperialviolet.org/2014/02/22/applebug.html

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DESIGN PRICIPLES

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KEEP IT SIMPLE STUPID!

@dgomezg

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Don’t Repeat Yourself

@dgomezg

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Separation OF Concerns

@dgomezg

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I: I

!

!

!

!

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SEPARATION OF CONCERNS DON’T REPEAT YOURSELF

@dgomezg

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ENSURING CODE QUALITY: THE QUALITY CYCLE

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Default Quality Cycle

@dgomezg

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Add Intermediate Quality Checks

@dgomezg

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Automate Intermediate Checks

@dgomezg

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Measure with tools

@dgomezg

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Define Business Key Indicators

@dgomezg

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Define Alarms

@dgomezg

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Get a Dashboard

@dgomezg

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Added Value: keeping everybody happy

@dgomezg

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TOOLS

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descriptor file +

source code +

Dependency Manager =

Artifact

Automated Build process

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TDD

http://reddevnews.com/articles/2007/11/01/testdriven-development-tdd.aspx

http://www.doolwind.com/blog/page/3/

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Jenkins Jobs to automate the build process: - On Events (commit) - Scheduled (cron expression) - Manually (upon request) !

Lots of plugins: - Release - Deploy - Customize dashboard - Trigger other checks

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SONARQbe (aka SONAR)

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SOME FINAL ADVICES

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Read! Keep your brain healthy

Clean Code:

Robert Martin (@unclebob)

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No Monkeys, No LizardsBe concious, be consequent

www.adictosaltrabajo.com/detalle-­‐noticia.php?noticia=356

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THe Software RUSTING principleThe software degrades slowly and slightly as time passes…

Sometimes is not slowly neither slightly!!

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The boy scout ruleTry and leave this world a little better than you found it, and when your turn comes to die you can die happy in feeling that at any rate you have not wasted your time but have done your best.

Robert Stephenson Smyth Baden-Powell

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Always code as if the person who ends up maintaining your code is a violent psychopath who knows where you live.

John F. Woods, September 1991

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Always code as if the person who ends up maintaining your code is a violent psychopath who knows where you live.

John F. Woods, September 1991

////////////////////////Manuela  Logger  log  =  LogFactory.getLogger(MyClass.class.getName());  ////////////////////////