<s>
PyObjC	B-Operating_System
is	O
a	O
bidirectional	O
bridge	O
between	O
the	O
Python	B-Language
and	O
Objective-C	B-Language
programming	I-Language
languages	I-Language
,	O
allowing	O
programmers	O
to	O
use	O
and	O
extend	O
existing	O
Objective-C	B-Language
libraries	B-Library
,	O
such	O
as	O
Apple	O
's	O
Cocoa	B-Operating_System
framework	B-Application
,	O
using	O
Python	B-Language
.	O
</s>
<s>
PyObjC	B-Operating_System
is	O
used	O
to	O
develop	O
macOS	B-Application
applications	O
in	O
pure	O
Python	B-Language
.	O
</s>
<s>
There	O
is	O
also	O
limited	O
support	O
for	O
GNUstep	B-Application
,	O
an	O
open	O
source	O
,	O
cross-platform	B-Operating_System
implementation	O
of	O
Cocoa	B-Operating_System
.	O
</s>
<s>
The	O
most	O
important	O
usage	O
of	O
PyObjC	B-Operating_System
is	O
enabling	O
programmers	O
to	O
create	O
GUI	B-Application
applications	O
using	O
Cocoa	B-Operating_System
libraries	B-Library
in	O
pure	O
Python	B-Language
.	O
</s>
<s>
Moreover	O
,	O
as	O
an	O
effect	O
of	O
Objective-C	B-Language
'	O
s	O
close	O
relationship	O
with	O
the	O
C	B-Language
programming	I-Language
language	I-Language
(	O
it	O
is	O
a	O
pure	O
superset	O
)	O
,	O
developers	O
are	O
also	O
able	O
to	O
incorporate	O
any	O
C-based	O
API	B-General_Concept
by	O
wrapping	O
it	O
with	O
an	O
Objective-C	B-Language
wrapper	O
and	O
then	O
using	O
the	O
wrapped	O
code	O
over	O
the	O
PyObjC	B-Operating_System
bridge	O
.	O
</s>
<s>
Using	O
Objective-C	B-Language
++	O
,	O
the	O
same	O
can	O
be	O
done	O
with	O
C%2B%2B	O
libraries	B-Library
.	O
</s>
<s>
Cocoa	B-Operating_System
developers	O
may	O
also	O
benefit	O
,	O
as	O
tasks	O
written	O
in	O
Python	B-Language
generally	O
take	O
fewer	O
lines	O
than	O
the	O
Objective-C	B-Language
equivalent	O
.	O
</s>
<s>
PyObjC	B-Operating_System
's	O
origins	O
date	O
back	O
to	O
1996	O
,	O
when	O
Lele	O
Gaifax	O
built	O
the	O
original	O
module	O
in	O
September	O
of	O
that	O
year	O
.	O
</s>
<s>
Among	O
the	O
credited	O
contributors	O
were	O
Guido	O
van	O
Rossum	O
,	O
creator	O
of	O
the	O
Python	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
PyObjC	B-Operating_System
was	O
rewritten	O
in	O
2002	O
.	O
Notable	O
additions	O
include	O
the	O
ability	O
to	O
directly	O
subclass	O
Objective-C	B-Language
classes	O
from	O
Python	B-Language
and	O
nearly	O
complete	O
support	O
for	O
the	O
Foundation	O
,	O
App	O
Kit	O
and	O
Address	O
Book	O
frameworks	O
.	O
</s>
<s>
Later	O
the	O
same	O
year	O
,	O
support	O
was	O
added	O
for	O
non-framework	O
Python	B-Language
builds	O
,	O
as	O
well	O
as	O
subsequent	O
support	O
for	O
the	O
Python	B-Language
distribution	O
included	O
with	O
Mac	B-Application
OS	I-Application
X	I-Application
.	O
</s>
<s>
Along	O
with	O
these	O
changes	O
came	O
project	O
templates	O
for	O
standalone	O
Cocoa	B-Operating_System
applications	O
for	O
use	O
with	O
Project	B-Operating_System
Builder	I-Operating_System
,	O
the	O
predecessor	O
to	O
the	O
current	O
Apple	O
platform	O
IDE	B-Application
,	O
Xcode	B-Operating_System
.	O
</s>
<s>
Apple	O
incorporated	O
PyObjC	B-Operating_System
into	O
Mac	B-Application
OS	I-Application
X	I-Application
in	O
2007	O
,	O
with	O
the	O
release	O
of	O
Mac	B-Application
OS	I-Application
X	I-Application
10.5	O
Leopard	O
.	O
</s>
<s>
In	O
Objective-C	B-Language
,	O
objects	O
communicate	O
with	O
each	O
other	O
by	O
sending	O
messages	O
,	O
which	O
is	O
analogous	O
to	O
method	O
calls	O
in	O
other	O
object-oriented	O
languages	O
.	O
</s>
<s>
This	O
is	O
distinct	O
from	O
the	O
syntax	O
used	O
in	O
Python	B-Language
,	O
and	O
in	O
many	O
other	O
languages	O
,	O
where	O
an	O
equivalent	O
expression	O
would	O
read	O
:	O
</s>
<s>
Translating	O
Objective-C	B-Language
selectors	O
to	O
Python	B-Language
method	O
names	O
is	O
accomplished	O
by	O
replacing	O
each	O
colon	O
with	O
a	O
single	O
underscore	O
and	O
listing	O
the	O
arguments	O
within	O
a	O
pair	O
of	O
parentheses	O
at	O
the	O
end	O
,	O
as	O
demonstrated	O
above	O
.	O
</s>
<s>
Objective-C	B-Language
classes	O
are	O
subclassed	O
in	O
the	O
same	O
manner	O
as	O
a	O
normal	O
Python	B-Language
class	O
:	O
</s>
