Measuring Code Quality in WTF/min.

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.

Except where otherwise noted, this work is licensed under: http://creativecommons.org/licenses/by-nc-sa/3.0/

Leganés!6-7 Febrero 2013!

http://creativecommons.org/licenses/by-nc-sa/3.0/

Measuring Code Quality: WTF/minLeganés!6-7 Febrero 2014

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@dgomezg


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Quality CODE RELATED CONCEPTS

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

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


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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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Some Misconceptions





@dgomezg


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Some Misconceptions





@dgomezg


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Some Misconceptions





@dgomezg


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Examples of real code from the real world

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@dgomezg


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@dgomezg

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)

/* */Measuring Code Quality: WTF/min

Leganés!6-7 Febrero 2014

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Comments are useful, butCOMMENTS

@dgomezg

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




@dgomezg

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




@dgomezg

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



COMMENTS: Remember to sign your code

@dgomezg

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



COMMENTS: A good marketing tool

@dgomezg

/** * 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(){

http://www.visitmywebsite.com



COMMENTS: FOOL THE code READEr

@dgomezg

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


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Exceptions are just that: ExceptionsExceptions

@dgomezg

Catch only if you can handle it

Declare the exact type

Don’t use for: Flow Control

State demarcation (other than Error)


Exceptions: Simply retrowing

@dgomezg

public 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; } }


Exceptions: NPE PARANOIA

@dgomezg

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

}

It’s better to check twice to avoid a NullPointerException

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

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


Exceptions: NPE PARANOIA

@dgomezg

It’s better to check twice to avoid a NullPointerException

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


Exceptions: Flow Control

@dgomezg

public class ProcesoTerminadoCorrectamenteException extends Exception { !}

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


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NAMING

@dgomezg

Use 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?

@dgomezg

if( p != null){ applyBusinessLogic(p,estado,manager); }

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


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UnNecessary code

@dgomezg

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

@dgomezg

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

.substringBefore(str, separator)); }


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UnNecessary code: Wrapping well-known APIs

@dgomezg

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


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UnNecessary code: Clever? Code

@dgomezg

/** 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;


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UnNecessary code: Clever? Code

@dgomezg

Challenge: Could you tell what will print the following code?

System.out.println(DOS * TRES);


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2K Effect… We miss you!

@dgomezg

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


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UnNecessary code: SOP

@dgomezg

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

Introducing SOP: String Oriented Programming


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UnNecessary code: TAKING ADVICE TOO SERIOUSLY

@dgomezg

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!!!


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UnNecessary code: The indentation MADNESS

@dgomezg

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


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DESIGN PRICIPLES

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KEEP IT SIMPLE STUPID!

@dgomezg


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Don’t Repeat Yourself

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Separation OF Concerns

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I: I

!

!

!

!

!

SEPARATION OF CONCERNS DON’T REPEAT YOURSELF

@dgomezg


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ENSURING CODE QUALITY: THE QUALITY CYCLE

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@dgomezg

Default Quality Cycle


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@dgomezg

Add Intermediate Quality Checks


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@dgomezg

Automate Intermediate Checks


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@dgomezg

Measure with tools


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@dgomezg

Define Business Key Indicators


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@dgomezg

Define Alarms


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@dgomezg

Get a Dashboard


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@dgomezg

Added Value: keeping everybody happy


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SOME FINAL ADVICES

@dgomezg


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Read! Keep your brain healthy

@dgomezg

Clean Code:

Robert Martin (@unclebob)


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No Monkeys, No Lizards

@dgomezg

Be concious, be consequent

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

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


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@dgomezg

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

Sometimes is not slowly neither slightly!!


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@dgomezg

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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@dgomezg

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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@dgomezg

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()); ////////////////////////

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Measuring Code Quality in WTF/min.

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