Guidelines to clean coding

GUIDELINES TO
CLEAN CODING
- Janak Porwal

“Most software today is very much like an
Egyptian pyramid with millions of bricks piled on
top of each other, with no structural integrity, but
just done by brute force and thousands of
slaves.”
-Alan Kay
SOFTWARE DEVELOPMENT

PROGRAMMING PRACTISES
“If builders built buildings the way programmers
wrote programs, then the first woodpecker that
came along would destroy civilization”
-Gerald Weinberg
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Evolution of a successful application
● “A successful application is going to be
used by real users”.

● “It is also likely to be augmented with more
features.”

features.”
● “More features More developers
More collaboration”

features.”
● “More features More developers
More collaboration”
● “Longer support”

PROGRAMMING PRACTISES WHY?
“Any fool can write code that a computer
can understand. Good programmers
write code that humans can understand”
- Martin Fowler

“Any code of your own that you haven't looked
at for six or more months might as well have
been written by someone else”.
- Eagleson's law
PROGRAMMING PRACTISES WHY?

WHAT IS A PROGRAM? ( And Evolution of Programming )
Programming = Instructions to control machines

Programming = Logical expressions to create
machine instructions

Programming = Language to express logic.

Programming = Description of a system

GOOD PROGRAM
“Measuring programming progress by lines of
code is like measuring aircraft design progress
by weight”
-Bill Gates
● Aim to reduce the number of lines of code to
a point that reducing it any further makes
the code unreadable.

GOOD PROGRAM
● Aim to reduce the number of lines of
code to a point that reducing it any
further makes the code unreadable.

Programming Guidelines
Thumb rules to write CREAM code
(Clean, Robust, Efficient and Modular)

AVOID CODE REPETITION
● “Avoid duplicating logic in your code”

● I repeat - “Avoid duplicating logic in your
code”

● I repeat - “Avoid duplicating logic in your
code”
function codingGyan() {
print “Avoid duplicating logic.”;
}
codingGyan();
I repeat - codingGyan();

if (direction == EAST) {
x = x + 10;
} else if(direction == WEST) {
x = x - 10;
} else if(direction == NORTH) {
y = y + 10;
} else if(direction == SOUTH) {
y = y - 10;
}
steps++;
strength--;
if (direction == EAST) {
x = x + 10;
steps++;
strength--;
} else if(direction == WEST) {
x = x - 10;
steps++;
strength--;
} else if(direction == NORTH) {
y = y + 10;
steps++;
strength--;
} else if(direction == SOUTH) {
y = y - 10;
steps++;
strength--;
}

GOOD PROGRAM
Aim to reduce the number of lines of code to a
point that reducing it any further makes the code
unreadable.
var a=b=c=d=e=o;
if ( expression ){Statement(s) to be executed if
expression is true }
Else{ Statement(s) to be executed if expression
is false }
var a;
if ( expression ){
statement(s) to be executed if expression is
true
}
Else{
Statement(s) to be executed if expression is
false
}

If a function/module/file starts to grow too
large, break it
SPLIT AND SOLVE

NO MAGIC NUMBERS : Code should be an art – not “black magic”.
int monthsToStock = 2;
int numberOfEmployees=26;
int notebooksPerMonth=1;
int quantity = monthsToStock *
numberOfEmployees *
notebooksPerMonth;
placeOrder(quantity);
placeOrder(52);

NO MAGIC NUMBERS
Advantages
● Better configurability

AVOID GLOBALS
Function 3
Function 1
Function 2
Function 4

● Good variables names bridge the gap
between machine language and human
language.
VARIABLE NAMING
var yellowBottle;
● Neither too short, nor too long. When in
doubt, use long.
var brightYellowMetalWaterBottle;
var b1;

WHAT'S IN A NAME?
var temp=[];
for(var i = 0; i < 10; i++) {
temp[i]=0;
}
function doSometing(x) {
var p=0;
var d=999999999;
for(var i = 0; i < 10; i++) {
if(d > temp[i]) {
d=temp[i];
p=i;
}
}
temp[p] += x;
}
var numQueues=10;
var queueBusyTill = [];
for(var nq = 0; nq < numQueues; nq++) {
queueBusyTill[nq]=0;
}
function chooseQueueForJob(jobDuration) {
var firstAvailableQueue=0;
var startTime=MAX;
for(var nq = 0; nq < numQueues; nq++) {
if(startTime > queueBusyTill[nq]) {
startTime=queueBusyTill[nq];
firstAvailableQueue=nq;
}
}
queueBusyTill[firstAvailableQueue] += jobDuration;
}

WHAT'S IN A NAME?
Bad code
temp = sqr ( b*b -4 *a *c );
root [0] = ( -b + temp ) / ( 2 * a );
root [1] = ( -b + temp ) / ( 2 * a );
...
temp = root [0];
root [0] = root [1];
root [1] = temp;
Better code
var discriminant = sqrt ( b * b - 4*a*c);
root [0] = ( -b + discriminant ) / ( 2 * a);
root [1] = ( -b - discriminant ) / ( 2 * a);
...
var oldRoot = root [0];
root [0] = root [1];
root [1] = oldRoot;
Use each variable for only one purpose !!!

As you’re about to add a comment, ask yourself,
‘How can I improve the code so that this comment
isn’t needed?'
● Add comments when the logic cannot be
deduced at a glance or there are tricky areas
● Code with documentation: roads without signs
● Avoid redundant comments
DOCUMENTATION AND COMMENTS
function addSalary(basic , pf, medical) {
Basic = 12 * grossSalary - pf + medical;
var sum = a + b; // add two numbers
}

● There are certain things programming
languages allow you to express.
● For everything else, there are
“programming conventions”
● File and folder structures, naming
conventions, etc.
● Familiarity helps.
CONSISTENCY

Avoid long list of parameters to functions.
● Split into smaller functions
● Share the variables (data members of a
class / module)
● Group together into a data object
LONG PARAMETER LIST
function iTakeLotsOfParameters(name, surname,
gender, age, city, email, phoneNumber, interestList)
{
print “Hello”, name;
}
function doTheSameThing(personDetails) {
print “Hello ”, personDetails[‘name’’];
}

Between classes / methods / files
TOO MUCH TALKING

“First – solve the problem. Then, write the
code.”
-John Johnson
PACING SOFTWARE DEVELOPMENT

Test matches -> One Day -> 20-20
FAST PACED WORLD

“Walking on water and developing software
from a specification are easy if both are
frozen.”
EVER CHANGING

Collaboration
● Self-organizing, cross-functional teams.
● Adaptive planning and evolutionary development
● Early delivery
● Continuous improvement
● Rapid and flexible response to change
● Plan -> Do -> Check -> Act
AGILE

“The word “Bug” is a lame attempt by software
people to blame someone else by implying that
mistakes somehow creep into the software from
outside while the developers are looking
elsewhere – as if it were not the developers who
made the mistakes in the first place.”
-Edsger W. Dijkstra
DEBUGGING

“It's hard enough to find an error in your code
when you're looking for it; it's even harder
when you've assumed your code is error-free.”
-Steve McConnell.
DEBUGGING

“When debugging, novices insert corrective
code; experts remove defective code.”
-Steve McConnell
DEBUGGING

“Computers are good at following instructions,
but not at reading your mind.”
-Donald Kruth
DEBUGGING

● Better to test incompletely than to
completely skip testing
● Think at the boundaries of the box
TESTING

To restructure software by applying a series of changes without
changing its (observable) behaviour
REFACTORING

● To restructure software by applying a
series of changes without changing its
(observable) behaviour
● Incremental, in short packets
REFACTORING

● To restructure software by applying a
series of changes without changing its
(observable) behaviour
● Incremental, in short packets
● Separate code clean-up, optimizations
and fixes
REFACTORING

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