<s>
Object	B-Application
schizophrenia	I-Application
or	O
self	O
schizophrenia	B-Application
is	O
a	O
complication	O
arising	O
from	O
delegation	B-Application
and	O
related	O
techniques	O
in	O
object-oriented	B-Language
programming	I-Language
,	O
where	O
self/this	O
can	O
refer	O
to	O
more	O
than	O
one	O
object	O
.	O
</s>
<s>
By	O
way	O
of	O
metaphor	O
with	O
the	O
public	O
confusion	O
of	O
dissociative	O
identity	O
disorder	O
with	O
the	O
psychiatric	O
diagnosis	O
of	O
schizophrenia	B-Application
,	O
the	O
former	O
being	O
associated	O
with	O
"	O
split	O
personalities	O
,	O
"	O
this	O
configuration	O
is	O
called	O
object	B-Application
schizophrenia	I-Application
or	O
self	O
schizophrenia	B-Application
in	O
object-oriented	B-Language
programming	I-Language
.	O
</s>
<s>
In	O
class-based	B-Application
programming	I-Application
,	O
objects	O
are	O
built	O
on	O
class	O
systems	O
,	O
where	O
an	O
object	O
is	O
an	O
instance	O
of	O
a	O
class	O
.	O
</s>
<s>
Classes	O
can	O
in	O
turn	O
be	O
related	O
by	O
inheritance	B-Language
:	O
a	O
base	O
class	O
provides	O
the	O
fundamental	O
or	O
default	O
behavior	O
of	O
an	O
object	O
,	O
and	O
acts	O
as	O
a	O
template	O
for	O
creating	O
objects	O
,	O
while	O
a	O
derived	O
class	O
can	O
be	O
used	O
to	O
override	O
behaviors	O
of	O
a	O
base	O
class	O
,	O
and	O
can	O
be	O
used	O
as	O
a	O
template	O
for	O
objects	O
whose	O
behaviors	O
refine	O
those	O
of	O
the	O
base	O
class	O
.	O
</s>
<s>
An	O
alternative	O
to	O
classes	O
and	O
inheritance	B-Language
is	O
prototypes	O
and	O
delegation	B-Application
,	O
which	O
is	O
used	O
in	O
prototype-based	B-Application
programming	I-Application
,	O
and	O
is	O
more	O
dynamic	O
.	O
</s>
<s>
Instead	O
of	O
using	O
one	O
class	O
to	O
refine	O
another	O
,	O
delegation	B-Application
allows	O
one	O
object	O
to	O
override	O
the	O
behavior	O
of	O
another	O
.	O
</s>
<s>
When	O
delegation	B-Application
is	O
used	O
,	O
the	O
question	O
arises	O
:	O
What	O
is	O
the	O
value	O
of	O
self	O
when	O
evaluating	O
a	O
method	O
on	O
object	O
a	O
,	O
which	O
is	O
delegated	O
to	O
a	O
method	O
on	O
object	O
b	O
?	O
</s>
<s>
HerrmannStephan	O
Herrmann	O
,	O
Demystifying	O
Object	B-Application
Schizophrenia	I-Application
,	O
in	O
Proceedings	O
of	O
MASPEGHI	O
Workshop	O
at	O
ECOOP	O
2010	O
reports	O
that	O
the	O
term	O
was	O
coined	O
by	O
William	O
Harrison	O
,	O
IBM	O
Research	O
,	O
around	O
May	O
1997	O
in	O
a	O
set	O
of	O
web	O
pages	O
,	O
which	O
discussed	O
problems	O
incurred	O
by	O
some	O
of	O
the	O
common	O
design	O
patterns	O
(	O
these	O
web	O
pages	O
are	O
no	O
longer	O
publicly	O
available	O
)	O
.	O
</s>
<s>
In	O
the	O
given	O
examples	O
the	O
problem	O
was	O
aggravated	O
by	O
the	O
fact	O
that	O
typical	O
solutions	O
would	O
use	O
a	O
weaker	O
form	O
of	O
delegation	B-Application
(	O
sometimes	O
called	O
forwarding	B-Application
)	O
where	O
knowledge	O
about	O
the	O
original	O
receiver	O
object	O
is	O
actually	O
lost	O
during	O
delegation	B-Application
.	O
</s>
<s>
Here	O
the	O
use	O
of	O
forwarding	B-Application
is	O
owed	O
to	O
the	O
fact	O
that	O
most	O
mainstream	O
object-oriented	B-Language
programming	I-Language
languages	I-Language
do	O
not	O
support	O
the	O
stronger	O
form	O
of	O
delegation	B-Application
.	O
</s>
<s>
Harrison	O
et	O
al	O
proposed	O
subject-oriented	B-Application
programming	I-Application
as	O
a	O
solution	O
,	O
which	O
by	O
static	O
composition	O
avoids	O
any	O
issues	O
of	O
object	B-Application
schizophrenia	I-Application
.	O
</s>
<s>
On	O
the	O
other	O
end	O
of	O
the	O
spectrum	O
,	O
Herrmann	O
shows	O
that	O
a	O
language	O
featuring	O
contextual	O
roles	B-General_Concept
can	O
be	O
designed	O
in	O
such	O
a	O
way	O
that	O
potential	O
problems	O
of	O
object	B-Application
schizophrenia	I-Application
are	O
essentially	O
irrelevant	O
despite	O
using	O
delegation	B-Application
as	O
a	O
means	O
to	O
share	O
behavior	O
between	O
a	O
role	O
object	O
and	O
its	O
associated	O
base	O
object''	O
.	O
</s>
