<s>
The	O
balking	B-Architecture
pattern	I-Architecture
is	O
a	O
software	O
design	O
pattern	O
that	O
only	O
executes	O
an	O
action	O
on	O
an	O
object	O
when	O
the	O
object	O
is	O
in	O
a	O
particular	O
state	O
.	O
</s>
<s>
For	O
example	O
,	O
if	O
an	O
object	O
reads	O
ZIP	B-General_Concept
files	I-General_Concept
and	O
a	O
calling	O
method	O
invokes	O
a	O
get	O
method	O
on	O
the	O
object	O
when	O
the	O
ZIP	B-General_Concept
file	I-General_Concept
is	O
not	O
open	O
,	O
the	O
object	O
would	O
"	O
balk	O
"	O
at	O
the	O
request	O
.	O
</s>
<s>
In	O
the	O
Java	B-Language
programming	I-Language
language	I-Language
,	O
for	O
example	O
,	O
an	O
IllegalStateException	O
might	O
be	O
thrown	O
under	O
these	O
circumstances	O
.	O
</s>
<s>
If	O
an	O
object	O
cannot	O
support	O
its	O
API	B-General_Concept
,	O
it	O
should	O
either	O
limit	O
the	O
API	B-General_Concept
so	O
that	O
the	O
offending	O
call	O
is	O
not	O
available	O
,	O
or	O
so	O
that	O
the	O
call	O
can	O
be	O
made	O
without	O
limitation	O
.	O
</s>
<s>
If	O
objects	O
are	O
to	O
remain	O
in	O
a	O
state	O
which	O
is	O
prone	O
to	O
balking	O
for	O
a	O
known	O
,	O
finite	O
period	O
of	O
time	O
,	O
then	O
the	O
guarded	B-General_Concept
suspension	I-General_Concept
pattern	I-General_Concept
may	O
be	O
preferred	O
.	O
</s>
<s>
Below	O
is	O
a	O
general	O
,	O
simple	O
example	O
for	O
an	O
implementation	O
of	O
the	O
balking	B-Architecture
pattern	I-Architecture
.	O
</s>
