1. Code Beauty
Prof. Fabio Kon
Department of Computer Science
Institute of Mathematics and Statistics
University of São Paulo
SugarLoafPLoP'2010 - 24/9/2010
Salvador, Brazil
1

2. Agenda
● Definition of Beauty
● Is Code Beauty important for Software
Development?
● What is Code Beauty
2

3. Beauty - Ancient View
● pre-socratic (e.g., Pythagoras): strong
connection among Beauty and Mathematics;
objects with proportions following the golden
ratio are more attractive to the human brain
● two quantities are in the golden ratio if the ratio of the
sum of the quantities to the larger quantity is equal to
the ratio of the larger quantity to the smaller one. The
golden ratio is an irrational mathematical constant,
approximately 1.6180339887
● greek architecture is based on symmetry and
on the golden ratio
3

4. Beauty - Romantic View
● works do not need to be harmoniously
proportioned and constitute a well-rounded
whole to be beautiful; on the contrary,
dissonance and fragmentation is beautiful
● more precisely: dissonance and fragmentation
allude to a harmony and wholeness that is not
in the work
4

5. Beauty - Modernist View
● architect Mies van der Rohe: “Less is More”
~ 1940
● designer Buckminster Fuller (geodesic dome)
adopted the engineer's goal of “Doing more
with less”
● writer Antoine de Saint Exupéry (1939)
“perfection is attained not when there is
nothing more to add, but when there is nothing
more to remove”
5

6. Beauty: Post-modernist view
● architect Robert Venturi: “Less is a Bore”, let's
do whatever people like
6

7. the greek and modernist views of beauty
provide us with a good basis for approaching
Beauty in Science and Technology
7

8. Science
make everything as simple as possible, but
not simpler
8

9. Technology
Conceptual integrity
– the architect or team of architects should
develop an idea of what the system should
do and make sure this vision is understood
by the rest of the team
– to ensure a user-friendly system, a system
may deliberately provide fewer features than
it is capable of
9

10. Beauty dictionary definition
the quality that gives pleasure to the mind or
senses and is associated with such properties
as
– harmony of form or color,
– excellence of artistry,
– truthfulness,
– and originality.
The American Heritage Dictionary of the
English Language, 4th Edition, 2000.
10

11. Does it matter?
Why are we talking about Code Beauty on a
“serious” Software Conference???
● personally, I have two reasons...
11

12. ● there has been a strong movement towards
managing software development projects as
any other production process/system
● many cases of managers that have never
written a single line of code
● is it possible to have a good Chef de Cuisine
that has never cooked in his life?
12

13. ● scientists/engineers/practitioners sometimes
tend to overestimate the power of science and
mathematics
● can science and engineering provide all what's
needed to explain life? and software
development?
13

14. What is Software Development?
– Modeling (Jacobsen)
– Engineering (Meyer)
– Discipline (Humphreys)
– Poetry (Cockburn)
– Craft (Knuth)
– Art (Gabriel)
(from from Alistair Cockburn)
● Common mistake: look at software as only
one of the above items.
14

15. ● our goal here, is to bring attention to a few
important aspects of software development
that are neglected in some software
engineering communities
● we'll look at the most important deliverable on
a software project:
The Code
15

16. Beauty is fundamental
vinicius de morais
Beautiful code
– brings pleasure to the reader
– makes the writer happy
– makes working in groups fun
This leads to
– fewer bugs
– maintainability
– team productivity
– in other words, Quality
16

17. In Software Development,
Beauty
Leads to
Quality
17

18. What is Beauty in
Software Development?
sources:
● Robert C. Martin. Clean Code - A Handbook of Agile
Software Craftsmanship. Prentice Hall. 2008.
● Andy Oram and Greg Wilson. Beautiful Code.
O'Reilly. 2007.
● beaute(code) art exhibit by Bob Hanmer, Karen
Hanmer, and Andrea Polli.
● exchange with experts
18

19. Rebecca Wirfs-Brock's code beauty
●it is a common recognition that these idioms and those
structures and those ways of doing things are of value
●it is important that a project or a team have the same
sense of aesthetics or there will be clashes of will
●keeping of every step in a method at the same level of
abstraction/intention; it reads much more like prose that
way
●characteristics that are "normally" present in beautiful
code are balance, effectiveness, expressiveness, and
profoundly doing well what it was designed to do.
19

20. Rebecca's example of a
beautiful code
● the Smalltalk class collection
●provide all the built in behavior by requiring subclasses to
implement three methods:
●add: anObject
●remove: anObject ifAbsent: exceptionBlock
●do: aBlock
● methods in the abstract class collection to add, remove,
check for emptiness, inclusion, occurrences, and to step
through a collection in different ways accumulating values…
are all implemented use these abstract building blocks or
invoking other defined behaviors that depend on these
implementation; elegant, beautiful reuse!
20

21. Joe Yoder's code beauty
● I think it is important to most of us who live there; it is like
cleaning up our living area, having clean code or beautiful
code can make life much better
●however let's face it, BBoM still thrive and exist and are
successful
●it matters, but is not necessary and sufficient for successful
software projects. If so, then Clean Code would become the
norm
● those of us who care strive for it because we believe it is
the right thing to do and it will help us in the long run...but
certain forces are in play that can make clean code or
beautiful code a goal that is very hard to achieve
21

22. Joe's example of a
beautiful code
● also the Smalltalk class collection
● you see a certain beauty and elegance in the
system as it was easy to understand and extend
● (it's also my favorite piece of code :-)
●design patterns can help with this as well; if a
system is clean and well designed by implementing
some of the best known principles and practices one
can see certain beauty in the system
22

23. W h a tis C l a n C ode ?
e
“I l m y co de t be e l e g a n t a nd
ike o
e ffi c i e n t. Th e l gic sh o ul be
o d
s t ra i g h forw a rd t m a ke it h a rd
o
fo r bugs to h ide , te
h
dependenc i es mi ni mal to
ease mai ntenanc e, e rror
h a n d l i n g c om p l e t e a cco rding t o
an a rt a t d
icul e st t gy,
ra e a nd
p e rform a n c e c l os e to op t i m a l
so a s not t t m p t p e op l t m a ke
o e e o
t e co de m e ssy w it unp rincip l d
h h e
op t iza t
im ions. Cl e a n c od e d oe s
on e t h i n g w e l l .”
Bjarne Stroustrup
Inventor of C++
23

24. W h a tis C l a n C ode ?
e
“C l a n co de is s i m p l e a nd d i re c t.
e
C l a n co de re a d s l i k e w e l l -
e
w ri t te n p ros e . C l a n code ne ve r
e
obscure s t e de signe r's int nt but
h e
ra t e r is ful o f crisp [cl a rl de fine d]
h l e y
a bst ct ns a nd s tra i g h forw a rd
ra io
l s o f co nt l ”
ine ro .
Grady Booch
Author of Object Oriented Analysis and
Design with Applications
24

25. W h a tis C l a n C ode ?
e
“Cl e a n c od e c a n b e re ad , a nd
e nh a nce d by a de ve l p e r o t e r t a n
o h h
it origina l a ut or I t h a s u n i t a n d
s h .
ac c eptanc e tests. It h a s
m e a n i n g fu l n am e s . It p rovide s
on e w a y ra t e r t a n m a ny w a ys
h h
fo r do ing o ne t ing. It h a s m i n i m a l
h
dependenc i es, w h ich a re
e xp l l de fine d, a nd p ro vide s a
icity
cl a r a nd m i n i m a l AP I . C ode
e
sh o ul be l i te ra t e since de p e nding
d
on t e l ngua ge , not a l ne ce ssa ry
h a l
info rm a t n ca n be e xp re sse d
io
Dave Thomas cl a rl in code a l ne . ”
e y o
Founder of OTI, godfather of
the Eclipse Strategy
25

26. W h a tis C l a n C ode ?
e
“I co ul l a l o f t e qua l ie s t a t I
d ist l h it h
no t ice in cl a n code , but t e re is
e h
one ove ra rch ing qua l y t a t l a ds t
it h e o
a l o f t e m . Cl e a n c od e a l w a ys
l h
l ook s i t w a s w ri t t e n b y
s om e on e w h o c a re s . Th e re i s
n ot h i n g obvi ou s t h a t you c a n
d o t o m a k e i t b e tt e r. A l of l
t o se t ings w e re t o ugh t a bo ut by
h h h
t e co de 's a ut or a nd if you t t
h h , ry o
im a gine im p ro ve m e nt yo u're l d
s, e
ba ck t w h e re you a re , siting in
o t
a p p re cia t n o f t e code som e one
io h
l ft fo r yo u – c od e l e ft b y
e
Michael Feathers
Author of Working Effectively s om e on e w h o c are s d e e p l y
With Legacy Code a b ou t th e c ra ft. ”
26

27. W h a tis C l a n C ode ?
e
“In re ce ntye a rs I be gin, a nd ne a rl y
e nd, w it B e ck's rul s of sim p l
h e e
co de . In p rio rit o rde r, sim p l code :
y e
•
R u n s al l t e s t s
•
Con ta i n s n o d u p l i c a t i on
•
E x p re s s e s al l t h e d e s i g n
i d e a s t a ta re in t e syst m
h h e
•
Mi n i m i ze s th e n u m b e r of
e n t i ti e s such a s cl sse s, m e t o ds,
a h
funct ions, a nd t e l . ”
h ike
Ron Jeffries
Author of Extreme
Programming Installed
27

28. W h a tis C l a n C ode ?
e
Y o u kno w you a re w orking on cl a n e
co de w h e n e a c h rou ti n e you
re a d tu rn s ou t t o be p re t t y
m u c h w h at you e x p e c t e d . Y o u
ca n ca l it b e a u t i fu l code w h e n t e
l h
co de s a l m a k e s i t l ook l i k e
so
t h e l a n g u a g e w a s m a d e for
t h e p rob l e m . ”
Ward Cunningham
Inventor of Wiki, Fit and much more
”Godfather of all those who care about code”
28

29. W h a tis C l a n C ode ?
e
W it outo bvio us
h
S im p le im p rove m e nt
s
E fficie nt
S t igh t rw a rd
ra fo
E xp re ssive
C o nt ins no
a
Turns outt be w h a t
o dup l t
ica ions
you e xp e ct d
e R uns a l t st
le s
F ul o f m e a ning
l L it ra l
e R e a ds w e ll
B e a u t i fu l : when M inim a l
th e l anguage was W rite n by
t
made for th e som e one w h o
p rob l e m ca re s
29

30. language may influence
/* C Language */
#include <stdio.h>
#define NumLines 10 /* number of lines */
main(argc,argv) int argc; char **argv;
{
int tri[NumLines][NumLines], /* triangle */
r,c,i; /* row, column, misc index */
/* initialize array */
for (r=0;r<NumLines;r++) {
tri[r][0]=1;
for (c=1;c<NumLines;c++) {
tri[r][c]=0;
};
/* generate triangle */
tri[0][0]=1;
for (r=1;r<NumLines;r++){
for (c=1;c<NumLines;c++) {
tri[r][c]=tri[r-1][c] + tri[r-1][c-1];
}
};
/* print triangle */
for (r=0;r<NumLines;r++){
for (i=0;i < ((NumLines-r-1)/2);i++) printf(" ");
if (r%2 == 0) printf(" ");
for (c=0;c<NumLines;c++){
if (tri[r][c] != 0) printf("%3d ",tri[r][c]);
};
printf("n");
}
}
source: http://www.andreapolli.com/beaute%28code%29/good_bad_ugly/pascal.html 30

31. let's get a little more technical
31

32. Me an i n g fu l
Names
32

33. M e a ningful N a m e s
N a m e s are vi t a l !
●
C ode is ba sica ly na m e s a nd re se rve d w o rds
l
● C h o o sing go od na m e s t ke s t e butsa ve s
a im
m o re t a n itt ke s
h a
● N a m e s sh oul be e xp re ssive a nd sh o ul
d d
a nsw e r que st ns
io
33

34. M e a ningful N a m e s
E xampl e
public List<int[]> getThem() {
List<int[]> list1 = new ArrayList<int[]>();
for (int[] x : theList)
if(x[0] == 4)
list1.add(x);
return list1;
}
34

35. M e a ningful N a m e s
E xampl e
public List<int[]> getThem() {
List<int[]> list1 = new ArrayList<int[]>();
for (int[] x : theList)
if(x[0] == 4)
list1.add(x);
return list1;
}
M a ny do ubt a rise . . .
s
1 . W h a tdoe s t is m e t od ge t
h h ?
2 . W h a tkinds o f t ings a re in t e L ist
h h ?
3. W h a tis t e im p ort nce of t e ze rot p osit
h a h h ion?
4. W h a tis t e significa nce o f t e va l 4?
h h ue
35

36. M e a ningful N a m e s
E xampl e
public List<int[]> getThem() {
List<int[]> list1 = new ArrayList<int[]>();
for (int[] x : theList)
if(x[0] == 4)
list1.add(x);
return list1;
}
W h a ta bo utt is
h
code ?
public List<int[]> getFlaggedCells() {
List<int[]> flaggedCells = new ArrayList<int[]>();
for (int[] cell : gameBoard)
if(cell[STATUS_VALUE] == FLAGGED)
flaggedCells.add(cell);
return flaggedCells;
}
36

37. M e a ningful N a m e s
E xampl e
public List<int[]> getFlaggedCells() {
List<int[]> flaggedCells = new ArrayList<int[]>();
for (int[] cell : gameBoard)
if(cell[STATUS_VALUE] == FLAGGED)
flaggedCells.add(cell);
return flaggedCells;
}
P robl m
e
sol d!
ve
1 . W h a tdo e s t is m e t o d ge t Itge t a l fl gge d ce ls!
h h ? s l a l
2 . W h a tkinds o f t ings a re in t e L ist t e L istis a ga m e B oa rd file d w it
h h ? h l h
ce ls!
l
3. W h a tis t e im p o rt nce of t e ze rot p osit n? Th a t t e S t t Va l !
h a h h io 's h a us ue
4. W h a tis t e significa nce o f t e va l 4? Itm e a ns itis fl gge d!
h h ue a
37

38. M e a ningful N a m e s
E xampl e
public List<int[]> getFlaggedCells() {
List<int[]> flaggedCells = new ArrayList<int[]>();
for (int[] cell : gameBoard)
if(cell[STATUS_VALUE] == FLAGGED)
flaggedCells.add(cell);
return flaggedCells;
}
G oing furt e r . .
h .
public List<Cell> getFlaggedCells() {
List<Cell> flaggedCells = new ArrayList<Cell>();
for (Cell cell : gameBoard)
if(cell.isFlagged())
flaggedCells.add(cell);
return flaggedCells; Th i s i s p re t ty
} muc h wh at
you
e x p e c te d ! 38

39. Ch a n g e s s h ou l d b e
e as y!
To m a ke ch a nge s, w e
ne e d t unde rst nd t e
o a h
●
Us e R e a d ab l e n am e s co de !
● X Y Z C o nt l rH a ndl
role ingO fS trings != X Y Z C ont le rS t ge O fS t
ro l ora rings
● Us e Se a rc h a b l e n am e s
●
Us e t h e L an g u ag e St an d a rd s
●
Us e Sol u t i on Dom a i n n a m e s
● U se p a te rn a nd a l
t gorit m na m e s, m a t t rm s, …
h h e
●
Us e P rob l e m Dom a i n n a m e s
●
Don 't c on fu s e t h e re a d e r
● U se t e ”O ne W ord P e r C o nce p t rul
h ” e
● D o n'tuse j s, m ind m a p p ings, h unga ria n no t t
oke a ion, . . .
39

40. M e a ningful N a m e s
Con c l u s i on
● itis e a sy t sa y t a tna m e s sh oul re ve a l int nt W h a t
o h d e .
w e w a ntt im p re ss up o n yo u is t a tw e a re s e rio us a bo ut
o h
t is
h
● sh o rtna m e s a re ge ne ra ly be te r t a n l nge r o ne s, so
l t h o
l ng a s t e y a re cl a r (do notp ro m o t obscurit t sa ve a
o h e e y o
co up l o f ke yst ke s)
e ro
●
i f you fi n d a b a d n a m e , c h a n g e i t n ow !
40

41. Fu n c t i on s
41

42. F unct
ions
Fu n c ti on s s h ou l d b e
smal l !
●
fu n c t i on s s h ou l d h a ve fe w l i n e s
● e a ch of t e m sh oul be o bvio us a nd e a sy t unde rst nd
h d o a
●
fu n c t i on s s h ou l d n ot h ol d n e s te d s t ru c t u re s
● if, w h il , e l bl cks sh o ul be st igh t
e se o d ra forw a rd
(p roba bl a funct ca l)
y ion l
● t e condit na l sh oul p roba bl be a funct n ca l t a te nca p sul t s it
h io d y io lh a e
42

43. F unct
ions
On e Th i n g !
F unct
ions sh oul do one t ing.
d h
Th e y sh oul do itw e l.
d l
Th e y sh o ul do itonl
d y.
●
fu n c ti on s t h a t d o on e t h i n g c an 't b e d i vi d e d i n t o s e c t i on s
●
t w o w a ys t o i d e n t i fy w h e th e r a fu n c t i on d oe s On e Th i n g
● if a funct do e s onl t ose st p s t a ta re one l ve l be l w t e st t d
ion y h e h e o h a e
na m e of t e funct
h ions, t e n t e funct ns is do ing one t ing
h h io h
● If you ca n'te xt cta no t e r funct n from itw it a na m e t a tis no t
ra h io h h
m e re l a re st t m e ntof it im p l m e nt t
y a e s e a ion, t e n it doing o ne t ing
h 's h
43

44. E xampl e
public void pay() {
for (Employee e : employees) {
if (e.isPayday()) {
Money pay = e.calculatePay();
e.deliverPay(pay);
}
}
}
Itdoe s m ore t a n one t ing. . .
h h
1 . itl op s ove r a l t e e m p l e s
o lh oye
2 . ch e cks t se e w h e t e r e a ch e m p l e ough tt be
o h oye o
p a ye d
3. p a ys t e e m p l ye e
h o
44

45. R e fa c t ore d
E xampl e
public void pay() {
for (Employee e : employees) Itj it ra t s ove r
ust e e
payIfNecessary(e); t e em pl es
h oye
}
private void payIfNecessary(Employee e) {
C h e cks w h e t e r a n
h
if (e.isPayday())
calculateAndDeliverPay();
e m p l e o ugh tt be p a id
oye o
}
private void
P a ys t e
h
calculateAndDeliverPay(Employee e) {
Money pay = e.calculatePay();
e m p l ye e
o
e.deliverPay(pay);
}
is this exaggerated?
45

46. F unct
ions
On e l e ve l of Ab s t ra c t i on
●
s t a t e m e n t s w i th i n a fu n c t i on s h ou l d b e a l l i n th e s a m e l e ve l
●
m i x i n g l e ve l s i s c on fu s i n g
● o nce de t il a re m ixe d w it e sse nt l conce p t m ore a nd m ore
a s h ia s,
de t il t nd t a ccre t w it in t e funct
a s e o e h h ions
● it t e firstst p t a rds t e cre a t of big funct
's h e ow h ion ions!
●
t h e St e p d ow n ru l e
● w e w a ntcode t re a d l a t -do w n na rra t
o ike op ive
46

47. F unct
ions
Fu n c ti on a rg u m e n t s
●
fu n c ti on s s h ou l d m i n i m i ze t h e n u m b e r of a rg u m e n ts
● a rgum e nt a re h a rd from a t st p o into f vie w
s e ing
● t o m a ny a rgum e nt = t e funct doe s m o re t a n o ne t ing
o s h ion h h
● t o m a ny a rgum e nt = t e funct is use d in m a ny diffe re ntw a ys
o s h ion
●
d on 't u s e fl ag arg u m e n t s
● itloudl p ro cl im s t a tt e funct
y a h h ions is doing m o re t a n one t ing
h h
47

48. F unct
ions
L as t b u t n ot l e a s t
●
fu n c ti on s s h ou l d n ot h a ve s i d e e ffe c t s
● t e y usua ly cre a t t m p ora l co up l
h l e e ing
●
itsh o ul cre a t a e ffe cton t e obj ctor re t so m e t ing
d e h e urn h
●
Don 't R e p e a t You rs e l f (DR Y)
● dup l t n m a y be t e rooto f a l e vil in soft a re
ica io h l w
functions sh o ul be sh ort w e l na m e d a nd nice l orga nize d
d , l y
48

49. Com m e n t s
”N o t ing ca n be quit so h e l ful a s a w e l-p l ce d com m e nt
h e p l a .
N o t ing ca n cl t r up a m odul t a n frivo l
h ute e h ous do gm a t
ic
co m m e nt N ot ing ca n be quit so da m a ging a s a n ol cruft
s. h e d y
co m m e ntt a tp rop a ga t s l s a nd m isinfo rm a t ”
h e ie ion.
49

50. C o m m e nt
s
Th e p rob l e m w i th c om m e n t s
●
c om m e n t s are , a t b e s t , n e c e s s ary e vi l
● t e p ro p e r use o f com m e nt is t co m p e nsa t for our fa il
h s o e ure t
o
e xp re ss o urse l in code ; no t t a tI use d t e w ord failure; I m e a ntit
f e h h
●
th ey l i e!
● p ro gra m m e rs ca n'tre a l ica ly m a int in t e m
ist l a h
● co m m e nt do n'ta l a ys folow t e code ch a nge s
s w l h
● t e y re quire a m a int na nce e ffo rtt a tt ke s t e
h e h a im
● t h ca n o nl be found in o ne p l ce : t e code
rut y a h
50

51. C o m m e nt
s
Cod e i s t h e on l y tru th
51

52. C o m m e nt
s
Good Com m e n ts
●
l e g a l c om m e n t s
●
in form a ti ve c om m e n t s
● C o m m e nt re gul r e xp re ssions ca n be quit use ful
ing a e
●
e x p l an at i on of i n t e n t an d c l a ri fi c at i on s
● som e de cisions a re n'tim p l m e nt t de cisions
e a ion
● w e h a ve t use l rie s t a ta re n'tso e xp re ssive
o ibra h
●
Am p l i fi c a ti on
● e xp l in h ow im p o rt nta n e l m e ntis
a a e
●
TODO Com m e n t s an d J avad oc s i n P u b l i c AP I
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53. 53

54. why should we write
beautiful code?
to feel good with ourselves
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55. Bibliography
● Wikipedia definition for Beauty, Golden Ratio,
Minimalism. 2010.
● Fred Brooks. The Mythical Man-Month:
Essays on Software Engineering. 1975.
● Dorthe Jørgensen. The Metamorphosis of
Beauty. 2002.
● The American Heritage Dictionary of the
English Language, 4th Edition, 2000.
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56. Bibliography
● Robert C. Martin. Clean Code - A Handbook of Agile
Software Craftsmanship. Prentice Hall. 2008.
● Andy Oram and Greg Wilson. Beautiful Code.
O'Reilly. 2007.
● beaute(code) art exhibit by Bob Hanmer, Karen
Hanmer, and Andrea Polli. Some material available at
http://karenhanmer.com/gallery/?gallery=beautecode
and http://www.andreapolli.com/beaute(code)
● Interviews with experts
● slides by João Machini de Miranda - IME/USP
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