1. Measuring Code Quality:
WTF/Minute
Real word examples of code that could give you a stroke
and some advices to not replicate them

2. About the speaker
David Gómez
Sw Architect & Trainer
dgomezg@autentia.com
@dgomezg

3. Code quality related
concepts

4. Code Quality:WTFs/lines of code
http://www.osnews.com/story/19266/WTFs_m

5. Code smells
A surface indication
that usually
corresponds to a
deeper problem in
the system
Term coined by Kent Beck

6. 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

7. Examples of real code
from the real world

8. Health warning!

9. Comments
Comments are useful, but
only if the add or explain the code.
Don’t describe what the code is doing
Explain why (pre/post-Conditions)
Use cases (for methods/types/functions)

10. Unuseful information

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

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

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

14. Comments as 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.hispersonaldomain.com/)
*
*/
reset: function(){

15. Fooling the reader with comments
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));
Fool the reader by commenting out only the if check
*For the trick to work out, keep the indentation

16. Exceptions/Errors
Exceptions are just that: Excepctions
Catch only if you can handle it
Don’t use for
Flow Control
State demarcation (Except error)

17. Simply retrhowing exceptions
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;
}
}

18. NPE Paranoia
It’s better to check twice in order to avoid a NullPointerException
while
(session
!=
null)
{
numSessions++
;
if
(session
!=
null)
{
...
}
...
}

19. NPE Paranoia
while (session != null) {
numSessions++ ;
if (session != null) {
//....
} else {
log.warn("Null session detected.” +
“ Starting session Synchronization");
//.... dead code follows...
}
}
It’s better to check twice in order to avoid a NullPointerException
Extra points if you add Dead code to an else block

20. Naming
Use descriptive names
Describe what a Class/Function/method
does, not what it means
Describe what a variable/attribute holds
Don’t use abreviations
Code for readability

21. What does this method do?
if(
p
!=
null){
applyBusinessLogic(p,estado,manager);
}
else
{
}
public
void
onButtonPressed(ActionEvent
e)
{
FormData
formData
=
parseFromEvent(e);
theAlgorithm(formData);
}

22. Unnecesary Code
Developers should be lazy
Don’t write code you don’t need
Don’t repeat yourself

23. Wrapping well know APIs
public
static
String
substringBefore(String
str,String
separator)
{
return
(org.apache.commons.lang.StringUtils
.substringBefore(str,
separator));
}
public
String
getPropiedad(String
clave)
{
return
wrappedCacheAdmin.getProperty(clave);
}
public
void
setClaseAlgoritmo(String
clase)
{
wrappedCacheAdmin.setAlgorithmClass(clase);
}

24. ¿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;

25. ¿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;
System.out.println(DOS
*
TRES);
Could you tell what will print the following code?

26. 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
2K Effect - We miss you!
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

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

28. Taking advice too seriously
Don’t push the recommendations to the limits
StringBuffer hql =
new StringBuffer(
"select distinct config from Config config ");
Query query = session.createQuery(hql.toString()) ;
String concatenation in Java is not recommended,
Use StringBuffer (or StringBuilder) instead

29. The indentation madness
}
});
}
}
});
}
});
}
}
]
}
},
]
});
});

30. Design principles

31. Keep It Simple Stupid!

32. Don’t Repeat Yourself

33. Separation of Concerns

34. 1:1
Separation Of Concerns
Don’t RepeatYourself

35. Tell,
Don’t Ask

36. Ensuring Code Quality
The Quality Cycle

37. The Quality Cycle

38. Checks at intermediary points

39. Checks at intermediary points

40. Tools: Measure

41. Define bussiness key points

42. Define alarms

43. Get a Dashboard

44. Added value

45. Some final advices

46. Clean
Code
Robert
Mar.n
(@unclebob)
John F. Woods, September 1991
Read! Keep your brain healty!

47. Be conscious, Be consequent
http://www.adictosaltrabajo.com/detalle-noticia.php?
noticia=356
No monkeys, no lizards

48. 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
Code for readability

49. 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
Code for readability
////////////////////////Manuela
Logger
log
=
LogFactory.getLogger(MyClass.class.getName());
////////////////////////
(Specially if you have your code signed)

50. Q&A