<s>
In	O
object-oriented	B-Language
programming	I-Language
,	O
a	O
programming	O
language	O
is	O
said	O
to	O
have	O
first-class	B-Application
messages	I-Application
or	O
dynamic	B-Application
messages	I-Application
if	O
in	O
a	O
method	B-Language
call	I-Language
not	O
only	O
the	O
receiving	O
object	O
and	O
parameter	O
list	O
can	O
be	O
varied	O
dynamically	O
(	O
i.e.	O
</s>
<s>
Typed	O
object-oriented	B-Language
programming	I-Language
languages	I-Language
,	O
such	O
as	O
Java	B-Language
and	O
C++	B-Language
,	O
often	O
do	O
not	O
support	O
first-class	O
methods	O
.	O
</s>
<s>
Smalltalk	B-Application
only	O
support	O
them	O
in	O
an	O
untyped	O
way	O
.	O
</s>
<s>
In	O
Objective-C	B-Language
(	O
Cocoa	B-Operating_System
)	O
,	O
you	O
can	O
use	O
to	O
represent	O
first-class	B-Application
messages	I-Application
in	O
a	O
way	O
that	O
is	O
aware	O
of	O
the	O
types	O
at	O
runtime	O
;	O
however	O
,	O
safe	O
use	O
still	O
relies	O
on	O
the	O
programmer	O
.	O
</s>
<s>
Some	O
theoretical	O
progress	O
has	O
been	O
made	O
to	O
support	O
first-class	B-Application
messages	I-Application
in	O
a	O
type-safe	B-Language
manner	O
,	O
but	O
none	O
of	O
the	O
proposed	O
systems	O
has	O
been	O
implemented	O
in	O
a	O
programming	O
language	O
,	O
possibly	O
due	O
to	O
their	O
complexity	O
.	O
</s>
