<s>
In	O
aspect-oriented	B-Architecture
software	I-Architecture
development	I-Architecture
,	O
cross-cutting	B-Application
concerns	I-Application
are	O
aspects	B-Application
of	O
a	O
program	B-Application
that	O
affect	O
several	O
modules	B-Architecture
,	O
without	O
the	O
possibility	O
of	O
being	O
encapsulated	B-Application
in	O
any	O
of	O
them	O
.	O
</s>
<s>
These	O
concerns	O
often	O
cannot	O
be	O
cleanly	O
decomposed	B-Architecture
from	O
the	O
rest	O
of	O
the	O
system	O
in	O
both	O
the	O
design	O
and	O
implementation	O
,	O
and	O
can	O
result	O
in	O
either	O
scattering	O
(	O
code	O
duplication	O
)	O
,	O
tangling	O
(	O
significant	O
dependencies	O
between	O
systems	O
)	O
,	O
or	O
both	O
.	O
</s>
<s>
For	O
instance	O
,	O
if	O
writing	O
an	O
application	B-Application
for	O
handling	O
medical	B-Application
records	I-Application
,	O
the	O
indexing	O
of	O
such	O
records	O
is	O
a	O
core	O
concern	O
,	O
while	O
logging	B-Application
a	O
history	O
of	O
changes	O
to	O
the	O
record	O
database	O
or	O
user	O
database	O
,	O
or	O
an	O
authentication	O
system	O
,	O
would	O
be	O
cross-cutting	B-Application
concerns	I-Application
since	O
they	O
interact	O
with	O
more	O
parts	O
of	O
the	O
program	B-Application
.	O
</s>
<s>
Cross-cutting	B-Application
concerns	I-Application
are	O
parts	O
of	O
a	O
program	B-Application
that	O
rely	O
on	O
or	O
must	O
affect	O
many	O
other	O
parts	O
of	O
the	O
system	O
.	O
</s>
<s>
They	O
form	O
the	O
basis	O
for	O
the	O
development	O
of	O
aspects	B-Application
.	O
</s>
<s>
Such	O
cross-cutting	B-Application
concerns	I-Application
do	O
not	O
fit	O
cleanly	O
into	O
object-oriented	B-Language
programming	I-Language
or	O
procedural	B-Application
programming	I-Application
.	O
</s>
<s>
Cross-cutting	B-Application
concerns	I-Application
can	O
be	O
directly	O
responsible	O
for	O
tangling	O
,	O
or	O
system	O
inter-dependencies	O
,	O
within	O
a	O
program	B-Application
.	O
</s>
<s>
Because	O
procedural	B-Application
and	O
functional	B-Language
language	I-Language
constructs	O
consist	O
entirely	O
of	O
procedure	O
calling	O
,	O
there	O
is	O
no	O
semantic	O
through	O
which	O
two	O
goals	O
(	O
the	O
capability	O
to	O
be	O
implemented	O
and	O
the	O
related	O
cross-cutting	B-Application
concern	I-Application
)	O
can	O
be	O
addressed	O
simultaneously	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
the	O
code	O
addressing	O
the	O
cross-cutting	B-Application
concern	I-Application
must	O
be	O
scattered	O
,	O
or	O
duplicated	O
,	O
across	O
the	O
various	O
related	O
locations	O
,	O
resulting	O
in	O
a	O
loss	O
of	O
modularity	B-Architecture
.	O
</s>
<s>
Aspect-oriented	B-Architecture
programming	I-Architecture
aims	O
to	O
encapsulate	B-Application
cross-cutting	B-Application
concerns	I-Application
into	O
aspects	B-Application
to	O
retain	O
modularity	B-Architecture
.	O
</s>
<s>
This	O
allows	O
for	O
the	O
clean	O
isolation	O
and	O
reuse	O
of	O
code	O
addressing	O
the	O
cross-cutting	B-Application
concern	I-Application
.	O
</s>
<s>
By	O
basing	O
designs	O
on	O
cross-cutting	B-Application
concerns	I-Application
,	O
software	B-General_Concept
engineering	I-General_Concept
benefits	O
can	O
include	O
modularity	B-Architecture
and	O
simplified	O
maintenance	O
.	O
</s>
