<s>
Software	B-General_Concept
construction	I-General_Concept
is	O
a	O
software	B-General_Concept
engineering	I-General_Concept
discipline	O
.	O
</s>
<s>
It	O
is	O
linked	O
to	O
all	O
the	O
other	O
software	B-General_Concept
engineering	I-General_Concept
disciplines	O
,	O
most	O
strongly	O
to	O
software	O
design	O
and	O
software	O
testing	O
.	O
</s>
<s>
Anticipating	O
change	O
helps	O
software	B-General_Concept
engineers	I-General_Concept
build	O
extensible	O
software	O
,	O
which	O
means	O
they	O
can	O
enhance	O
a	O
software	O
product	O
without	O
disrupting	O
the	O
underlying	O
structure	O
.	O
</s>
<s>
Research	O
over	O
25	O
years	O
showed	O
that	O
the	O
cost	O
of	O
rework	O
can	O
be	O
10	O
to	O
100	O
times	O
(	O
5	O
to	O
10	O
times	O
for	O
smaller	O
projects	O
)	O
more	O
expensive	O
than	O
getting	O
the	O
requirements	B-General_Concept
right	O
the	O
first	O
time	O
.	O
</s>
<s>
Given	O
that	O
25%	O
of	O
the	O
requirements	B-General_Concept
change	O
during	O
development	O
on	O
average	O
project	O
,	O
the	O
need	O
to	O
reduce	O
the	O
cost	O
of	O
rework	O
elucidates	O
the	O
need	O
for	O
anticipating	O
change	O
.	O
</s>
<s>
Constructing	O
for	O
verification	O
means	O
building	O
software	O
in	O
such	O
a	O
way	O
that	O
faults	O
can	O
be	O
ferreted	O
out	O
readily	O
by	O
the	O
software	B-General_Concept
engineers	I-General_Concept
writing	O
the	O
software	O
,	O
as	O
well	O
as	O
during	O
independent	O
testing	O
and	O
operational	O
activities	O
.	O
</s>
<s>
Specific	O
techniques	O
that	O
support	O
constructing	O
for	O
verification	O
include	O
following	O
coding	O
standards	O
to	O
support	O
code	O
reviews	O
,	O
unit	O
testing	O
,	O
organizing	O
code	O
to	O
support	O
automated	B-Application
testing	I-Application
,	O
and	O
restricted	O
use	O
of	O
complex	O
or	O
hard-to-understand	O
language	O
structures	O
,	O
among	O
others	O
.	O
</s>
<s>
Tools	O
:	O
Such	O
as	O
diagrammatic	O
standards	O
for	O
notations	O
like	O
UML	B-Language
.	O
</s>
<s>
These	O
models	O
treat	O
construction	O
as	O
an	O
activity	O
which	O
occurs	O
only	O
after	O
significant	O
prerequisite	O
work	O
has	O
been	O
completed	O
—	O
including	O
detailed	O
requirements	B-General_Concept
work	O
,	O
extensive	O
design	O
work	O
,	O
and	O
detailed	O
planning	O
.	O
</s>
<s>
These	O
approaches	O
tend	O
to	O
treat	O
construction	O
as	O
an	O
activity	O
that	O
occurs	O
concurrently	O
with	O
other	O
software	O
development	O
activities	O
,	O
including	O
requirements	B-General_Concept
,	O
design	O
,	O
and	O
planning	O
,	O
or	O
overlaps	O
them	O
.	O
</s>
<s>
Requirements	B-General_Concept
analysis	O
,	O
Software	O
design	O
,	O
..	O
</s>
<s>
Construction	O
planning	O
also	O
defines	O
the	O
order	O
in	O
which	O
components	O
are	O
created	O
and	O
integrated	O
,	O
the	O
software	B-Application
quality	I-Application
management	I-Application
processes	O
,	O
the	O
allocation	O
of	O
task	O
assignments	O
to	O
specific	O
software	B-General_Concept
engineers	I-General_Concept
,	O
and	O
the	O
other	O
tasks	O
,	O
according	O
to	O
the	O
chosen	O
method	O
.	O
</s>
<s>
Software	B-General_Concept
construction	I-General_Concept
is	O
driven	O
by	O
many	O
practical	O
considerations	O
:	O
</s>
<s>
In	O
order	O
to	O
account	O
for	O
the	O
unanticipated	O
gaps	O
in	O
the	O
software	O
design	O
,	O
during	O
software	B-General_Concept
construction	I-General_Concept
some	O
design	O
modifications	O
must	O
be	O
made	O
on	O
a	O
smaller	O
or	O
larger	O
scale	O
to	O
flesh	O
out	O
details	O
of	O
the	O
software	O
design	O
.	O
</s>
<s>
They	O
include	O
configuration	O
languages	O
,	O
toolkit	B-Library
languages	O
,	O
and	O
programming	O
languages	O
:	O
</s>
<s>
Configuration	O
languages	O
are	O
languages	O
in	O
which	O
software	B-General_Concept
engineers	I-General_Concept
choose	O
from	O
a	O
limited	O
set	O
of	O
predefined	O
options	O
to	O
create	O
new	O
or	O
custom	O
software	O
installations	O
.	O
</s>
<s>
Toolkit	B-Library
languages	O
are	O
used	O
to	O
build	O
applications	O
out	O
of	O
toolkits	B-Library
and	O
are	O
more	O
complex	O
than	O
configuration	O
languages	O
.	O
</s>
<s>
Scripting	B-Language
languages	I-Language
are	O
kinds	O
of	O
application	O
programming	O
languages	O
that	O
supports	O
scripts	O
which	O
are	O
often	O
interpreted	O
rather	O
than	O
compiled	O
.	O
</s>
<s>
Linguistic	O
notations	O
which	O
are	O
distinguished	O
in	O
particular	O
by	O
the	O
use	O
of	O
word-like	O
strings	O
of	O
text	O
to	O
represent	O
complex	O
software	B-General_Concept
constructions	I-General_Concept
,	O
and	O
the	O
combination	O
of	O
such	O
word-like	O
strings	O
into	O
patterns	O
that	O
have	O
a	O
sentence-like	O
syntax	O
.	O
</s>
<s>
The	O
following	O
considerations	O
apply	O
to	O
the	O
software	B-General_Concept
construction	I-General_Concept
coding	O
activity	O
:	O
</s>
<s>
Use	O
of	O
classes	O
,	O
enumerated	B-Language
types	I-Language
,	O
variables	O
,	O
named	O
constants	O
,	O
and	O
other	O
similar	O
entities	O
:	O
</s>
<s>
A	O
study	O
done	O
by	O
NASA	O
showed	O
that	O
the	O
putting	O
the	O
code	O
into	O
well-factored	O
classes	O
can	O
double	O
the	O
code	O
reusability	B-Application
compared	O
to	O
the	O
code	O
developed	O
using	O
functional	O
design	O
.	O
</s>
<s>
Another	O
study	O
of	O
a	O
different	O
450	O
routines	O
found	O
that	O
routines	O
with	O
the	O
highest	O
coupling-to-cohesion	O
ratios	O
had	O
7	O
times	O
as	O
many	O
errors	O
as	O
those	O
with	O
the	O
lowest	O
coupling-to-cohesion	O
ratios	O
and	O
were	O
20	O
times	O
as	O
costly	O
to	O
fix	O
.	O
</s>
<s>
Source	O
code	O
organization	O
(	O
into	O
classes	O
,	O
packages	B-Language
,	O
or	O
other	O
structures	O
)	O
.	O
</s>
<s>
When	O
considering	O
inheritance	B-Language
,	O
the	O
number	O
of	O
levels	O
in	O
the	O
inheritance	B-Language
tree	O
should	O
be	O
limited	O
.	O
</s>
<s>
Deep	O
inheritance	B-Language
trees	O
have	O
been	O
found	O
to	O
be	O
significantly	O
associated	O
with	O
increased	O
fault	O
rates	O
.	O
</s>
<s>
Construction	O
involves	O
two	O
forms	O
of	O
testing	O
,	O
which	O
are	O
often	O
performed	O
by	O
the	O
software	B-General_Concept
engineer	I-General_Concept
who	O
wrote	O
the	O
code	O
:	O
</s>
<s>
Implementing	O
software	O
reuse	O
entails	O
more	O
than	O
creating	O
and	O
using	O
libraries	B-Library
of	O
assets	O
.	O
</s>
<s>
The	O
tasks	O
related	O
to	O
reuse	O
in	O
software	B-General_Concept
construction	I-General_Concept
during	O
coding	O
and	O
testing	O
are	O
:	O
</s>
<s>
The	O
selection	O
of	O
the	O
reusable	O
units	O
,	O
databases	B-Application
,	O
test	O
procedures	O
,	O
or	O
test	B-General_Concept
data	I-General_Concept
.	O
</s>
<s>
The	O
evaluation	O
of	O
code	O
or	O
test	O
re-usability	B-Application
.	O
</s>
<s>
The	O
reporting	O
of	O
reuse	O
information	O
on	O
new	O
code	O
,	O
test	O
procedures	O
,	O
or	O
test	B-General_Concept
data	I-General_Concept
.	O
</s>
<s>
Object-oriented	O
languages	O
support	O
a	O
series	O
of	O
runtime	O
mechanisms	O
that	O
increase	O
the	O
flexibility	O
and	O
adaptability	O
of	O
the	O
programs	O
like	O
data	O
abstraction	O
,	O
encapsulation	B-Application
,	O
modularity	B-Architecture
,	O
inheritance	B-Language
,	O
polymorphism	B-Application
,	O
and	O
reflection	B-Language
.	O
</s>
<s>
Design	B-Application
by	I-Application
contract	I-Application
is	O
a	O
development	O
approach	O
in	O
which	O
preconditions	O
and	O
postconditions	O
are	O
included	O
for	O
each	O
routine	O
.	O
</s>
<s>
Defensive	B-Application
programming	I-Application
is	O
the	O
protection	O
a	O
routine	O
from	O
being	O
broken	O
by	O
invalid	O
inputs	O
.	O
</s>
<s>
Exception-handling	O
is	O
a	O
programming-language	O
construct	O
or	O
hardware	O
mechanism	O
designed	O
to	O
handle	O
the	O
occurrence	O
of	O
exceptions	B-General_Concept
,	O
special	O
conditions	O
that	O
change	O
the	O
normal	O
flow	O
of	O
program	O
execution	O
.	O
</s>
<s>
Fault	B-General_Concept
tolerance	I-General_Concept
is	O
a	O
collection	O
of	O
techniques	O
that	O
increase	O
software	O
reliability	O
by	O
detecting	O
errors	O
and	O
then	O
recovering	O
from	O
them	O
if	O
possible	O
or	O
containing	O
their	O
effects	O
if	O
recovery	O
is	O
not	O
possible	O
.	O
</s>
<s>
Internationalization	B-General_Concept
is	O
the	O
technical	O
activity	O
of	O
preparing	O
a	O
program	O
,	O
usually	O
interactive	O
software	O
,	O
to	O
support	O
multiple	O
locales	O
.	O
</s>
<s>
The	O
corresponding	O
activity	O
,	O
localization	B-General_Concept
,	O
is	O
the	O
activity	O
of	O
modifying	O
a	O
program	O
to	O
support	O
a	O
specific	O
local	O
language	O
.	O
</s>
