Measuring Code Quality in WTF/min.

Leganés!
6-7 Febrero 2013!

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/

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6-7 Febrero 2014


@dgomezg

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6-7 Febrero 2014


@dgomezg

Quality CODE
RELATED CONCEPTS

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@dgomezg

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

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6-7 Febrero 2014


@dgomezg

CODE SMELL
A surface indication
that usually
corresponds to a
deeper problem in the
system
Term coined by Kent Beck
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6-7 Febrero 2014


@dgomezg

Some Misconceptions
You write code for a computer to read
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
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6-7 Febrero 2014


@dgomezg

Examples of real code
from the real world

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@dgomezg

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6-7 Febrero 2014


@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)
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6-7 Febrero 2014


@dgomezg

COMMENTS
Comments are useful, but

/* */
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)

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6-7 Febrero 2014


COMMENTS: Unuseful info

@dgomezg

/* */

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6-7 Febrero 2014


@dgomezg


/* */
/**

* Método get Disponibilidad.

*

* @return Returns the disponibilidad.

*/
public String getDisponibilidad() {

//
//

}

We will get back to the implementation detail
More fun later

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6-7 Febrero 2014



@dgomezg

/* */

!

/** Atributo codCircuito. */
private String codCircuito;

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

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6-7 Febrero 2014


@dgomezg

COMMENTS:
Remember to sign your code

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

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6-7 Febrero 2014


@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(){

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6-7 Febrero 2014


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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6-7 Febrero 2014


@dgomezg

Exceptions
Exceptions are just that: Exceptions
Catch only if you can handle it
Declare the exact type
Don’t use for:
Flow Control
State demarcation (other than Error)
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6-7 Febrero 2014


@dgomezg

Exceptions: Simply retrowing
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;
}
}

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6-7 Febrero 2014


Exceptions: NPE PARANOIA

@dgomezg

It’s better to check twice to avoid a NullPointerException

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

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6-7 Febrero 2014


@dgomezg

Exceptions: NPE PARANOIA

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...
}
}

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

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6-7 Febrero 2014


@dgomezg

Exceptions: Flow Control
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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6-7 Febrero 2014


@dgomezg

NAMING
Use descriptive names
Describe what a Class/function/method does,
not what it means
Describe what a variable/attribute holds
Don’t use abbreviations
Code for readability
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6-7 Febrero 2014


@dgomezg

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

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

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@dgomezg

UnNecessary code
Developers should be lazy
Don’t write code you don’t need
Don’t repeat yourself

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@dgomezg

UnNecessary code:
Wrapping well-known APIs
public static String substringBefore(String str,String separator) {
return (org.apache.commons.lang.StringUtils
.substringBefore(str, separator));
}

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6-7 Febrero 2014


@dgomezg

UnNecessary code:
Wrapping well-known APIs

public String getPropiedad(String clave) {
return wrappedCacheAdmin.getProperty(clave);
}

public void setClaseAlgoritmo(String clase) {
wrappedCacheAdmin.setAlgorithmClass(clase);
}

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6-7 Febrero 2014


@dgomezg

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;

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6-7 Febrero 2014


@dgomezg

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

System.out.println(DOS * TRES);

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6-7 Febrero 2014


@dgomezg

2K Effect… We miss you!
NODO 1

!
# Planificacion Procesos Batch
# (Formato ss mm hh dd MM yyyy)
NODO 3
#
cron.sync=0 00 15 * * ? !
cron.download=0 00 23 * * ? 2030
NODO 4
cron.reports=0 00 23 * * ? 2030
!
#
!
cron.sync=0 00 16 * * ?
cron.download=0 00 03 * * ? 2030
cron.reports=0 00 03 * * ? 2030
#
cron.sync=0 00 12 * * ?
cron.download=0 00 12 * * 2030
cron.reports=0 00 12 * * 2030

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6-7 Febrero 2014


@dgomezg

UnNecessary code: SOP
Introducing SOP: String Oriented Programming

/**
* Método get Disponibilidad.
*
* @return Returns the disponibilidad.
*/
public String getDisponibilidad() {
if (numeroPuestos == 0)
return "No";
else return "Si";
}
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6-7 Febrero 2014


@dgomezg

UnNecessary code:
TAKING ADVICE TOO SERIOUSLY
String concatenation in Java is not recommended.
Use StringBuffer or StringBuilder instead
StringBuffer 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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6-7 Febrero 2014

@dgomezg


UnNecessary code:
The indentation MADNESS

]
});
});

},

}

]

}

}

}
});

});

}
});
}
}

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@dgomezg

DESIGN PRICIPLES

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@dgomezg


K IS S
EEP

T

IMPLE

TUPID!
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@dgomezg


D R Y
on’t

epeat

ourself
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@dgomezg


S OC
eparation

F

oncerns
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I:I

@dgomezg

!
!
!
!
!

SEPARATION OF CONCERNS
DON’T REPEAT YOURSELF
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@dgomezg

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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Define Alarms

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Get a Dashboard

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@dgomezg

Added Value: keeping everybody happy

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@dgomezg

SOME FINAL ADVICES

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@dgomezg

Read! Keep your brain healthy
Clean Code:
Robert Martin (@unclebob)

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@dgomezg

No Monkeys, No Lizards
Be concious, be consequent

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

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@dgomezg

THe Software RUSTING principle
The software degrades slowly and slightly as
time passes…
Sometimes is not slowly neither slightly!!

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6-7 Febrero 2014


@dgomezg

The boy scout rule
Try 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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6-7 Febrero 2014


@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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6-7 Febrero 2014


@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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