<s>
The	O
TnFOX	B-Language
portability	O
toolkit	O
is	O
a	O
fork	O
of	O
the	O
FOX	B-Language
GUI	B-Library
toolkit	I-Library
with	O
most	O
of	O
the	O
added	O
code	O
implementing	O
orthogonal	O
features	O
(	O
i.e.	O
</s>
<s>
not	O
substantially	O
changing	O
the	O
FOX	B-Language
API	O
)	O
such	O
that	O
applications	O
developed	O
for	O
FOX	B-Language
can	O
be	O
easily	O
recompiled	O
for	O
TnFOX	B-Language
.	O
</s>
<s>
Unusually	O
,	O
TnFOX	B-Language
also	O
contains	O
API	O
emulations	O
of	O
some	O
Qt	B-Language
library	I-Language
classes	O
-	O
according	O
to	O
the	O
author	O
,	O
this	O
was	O
done	O
to	O
port	O
a	O
substantial	O
project	O
from	O
Qt	B-Language
to	O
FOX	B-Language
.	O
</s>
<s>
Most	O
of	O
the	O
added	O
features	O
implement	O
a	O
full	O
"	O
portability	O
toolkit	O
"	O
library	O
such	O
that	O
one	O
can	O
write	O
one	O
program	O
to	O
run	O
anywhere	O
-	O
this	O
differs	O
from	O
FOX	B-Language
which	O
mostly	O
just	O
provides	O
the	O
GUI	O
portability	O
alone	O
.	O
</s>
<s>
TnFOX	B-Language
is	O
therefore	O
an	O
example	O
of	O
an	O
operating	B-Operating_System
system	I-Operating_System
abstraction	I-Operating_System
layer	I-Operating_System
.	O
</s>
<s>
Unlike	O
FOX	B-Language
,	O
TnFOX	B-Language
supports	O
only	O
a	O
restricted	O
set	O
of	O
C++	B-Language
compilers	O
and	O
operating	O
systems	O
.	O
</s>
<s>
It	O
only	O
supports	O
Microsoft	B-Application
's	I-Application
C++	I-Application
compiler	I-Application
v7.1	O
and	O
later	O
,	O
GCC	B-Application
v3.2	O
and	O
later	O
and	O
Intel	B-Language
C++	I-Language
compiler	I-Language
v8	O
or	O
later	O
.	O
</s>
<s>
It	O
also	O
only	O
runs	O
on	O
Windows	B-Application
2000	I-Application
or	O
later	O
,	O
Linux	B-Application
2.6	O
kernels	O
or	O
later	O
,	O
FreeBSD	B-Operating_System
and	O
Mac	O
OS	O
X	O
10.4	O
or	O
later	O
,	O
though	O
on	O
any	O
processor	O
or	O
architecture	O
.	O
</s>
<s>
TnFOX	B-Language
contains	O
its	O
own	O
automatically	O
generated	O
bindings	O
for	O
Python	B-Language
based	O
on	O
Boost.Python	O
library	O
-	O
such	O
were	O
the	O
complexity	O
of	O
these	O
it	O
required	O
adding	O
the	O
-fvisibility	O
feature	O
to	O
GCC	B-Application
v4	O
onwards	O
.	O
</s>
<s>
One	O
of	O
the	O
more	O
original	O
features	O
of	O
TnFOX	B-Language
is	O
its	O
heavy	O
usage	O
of	O
C++	B-Application
metaprogramming	I-Application
though	O
this	O
is	O
entirely	O
kept	O
away	O
from	O
the	O
GUI	O
side	O
of	O
things	O
(	O
for	O
FOX	B-Language
compatibility	O
)	O
.	O
</s>
<s>
A	O
full	O
lightweight	O
metaprogramming	B-Application
toolkit	O
is	O
included	O
which	O
allows	O
many	O
of	O
the	O
operations	O
provided	O
by	O
the	O
Boost	B-Language
metaprogramming	B-Application
library	O
,	O
including	O
typelists	O
,	O
type	O
traits	O
,	O
compile-time	O
logic	O
,	O
functors	O
,	O
virtual	O
table	O
compilation	O
,	O
horizontal	O
type	O
list	O
instantiation	O
and	O
more	O
.	O
</s>
<s>
Unlike	O
Boost	B-Language
,	O
due	O
to	O
the	O
requirement	O
for	O
a	O
modern	O
C++	B-Language
compiler	O
,	O
all	O
the	O
metaprogramming	B-Application
operates	O
consistently	O
across	O
compilers	O
without	O
the	O
need	O
for	O
ugly	O
macros	O
.	O
</s>
<s>
Another	O
unusual	O
feature	O
is	O
the	O
use	O
of	O
pervasive	O
exception	B-General_Concept
handling	I-General_Concept
and	O
safety	O
whereby	O
any	O
line	O
is	O
assumed	O
to	O
always	O
potentially	O
throw	O
an	O
exception	O
.	O
</s>
<s>
TnFOX	B-Language
provides	O
a	O
C++	B-Language
rollback	O
mechanism	O
(	O
as	O
originally	O
proposed	O
by	O
Andrei	O
Alexandrescu	O
)	O
to	O
keep	O
track	O
of	O
what	O
operations	O
need	O
to	O
be	O
undone	O
at	O
any	O
given	O
stage	O
should	O
an	O
error	O
occur	O
-	O
rather	O
like	O
a	O
SQL	B-Language
transaction	O
.	O
</s>
<s>
One	O
problem	O
with	O
this	O
approach	O
is	O
the	O
possibility	O
of	O
nested	O
exception	O
throws	O
during	O
object	O
destruction	O
which	O
under	O
the	O
ISO	O
C++	B-Language
standard	O
requires	O
an	O
immediate	O
program	O
termination	O
-	O
TnFOX	B-Language
works	O
around	O
this	O
problem	O
via	O
preprocessing	O
of	O
the	O
source	O
to	O
add	O
extra	O
support	O
code	O
.	O
</s>
<s>
A	O
quirky	O
addition	O
of	O
the	O
v0.88	O
release	O
is	O
to	O
use	O
Google	B-Application
Translate	I-Application
to	O
convert	O
its	O
locale	O
strings	O
.	O
</s>
<s>
Unlike	O
most	O
portability	O
toolkits	O
,	O
TnFOX	B-Language
has	O
been	O
very	O
extensively	O
profiled	O
and	O
performance	O
tuned	O
for	O
maximum	O
speed	O
and	O
minimal	O
memory	O
usage	O
.	O
</s>
<s>
It	O
optionally	O
uses	O
its	O
own	O
thread	O
caching	O
memory	O
allocator	O
,	O
automatically	O
uses	O
dynamic	O
algorithms	O
which	O
will	O
trade	O
speed	O
for	O
memory	O
usage	O
according	O
to	O
memory	O
low	O
conditions	O
and	O
has	O
very	O
strong	O
x86	O
and	O
x64	O
specific	O
optimisations	O
including	O
a	O
metaprogramming	B-Application
implementation	O
of	O
SIMD	O
vectors	O
which	O
will	O
automatically	O
compile	O
down	O
into	O
SSE	O
operations	O
(	O
right	O
up	O
to	O
SSE4	O
support	O
)	O
.	O
</s>
<s>
It	O
has	O
its	O
own	O
assembler	O
written	O
fast	O
mutex	O
implementation	O
,	O
extensive	O
internal	O
caching	O
to	O
avoid	O
syscalls	O
to	O
the	O
kernel	O
and	O
its	O
own	O
inter-process	O
communication	O
framework	O
which	O
can	O
transport	O
arbitrary	O
C++	B-Language
object	O
instances	O
from	O
one	O
place	O
to	O
another	O
by	O
leveraging	O
metaprogramming	B-Application
to	O
automatically	O
implement	O
serialisation	O
&	O
deserialisation	O
.	O
</s>
<s>
This	O
is	O
particularly	O
evident	O
in	O
its	O
SQL	B-Language
database	I-Language
interface	O
where	O
one	O
can	O
simply	O
bind	O
an	O
arbitrary	O
C++	B-Language
object	O
instance	O
to	O
a	O
BLOB	O
field	O
and	O
no	O
further	O
code	O
is	O
required	O
.	O
</s>
<s>
TnFOX	B-Language
optionally	O
includes	O
copies	O
of	O
the	O
OpenSSL	B-Language
library	O
and	O
the	O
SQLite	B-Language
library	O
in	O
order	O
to	O
implement	O
its	O
strong	O
encryption	O
and	O
its	O
default	O
SQL	B-Language
database	I-Language
implementation	O
respectively	O
.	O
</s>
<s>
TnFOX	B-Language
has	O
already	O
begun	O
to	O
add	O
C++0x	B-Language
features	O
for	O
those	O
compilers	O
which	O
support	O
them	O
-	O
this	O
being	O
the	O
next	O
revision	O
of	O
the	O
ISO	O
C++	B-Language
standard	O
.	O
</s>
