Well you can, as this illustrates:
typedef class
{
public:
int bar;
} tFoo;
tFoo a;
void handler ()
{
a.bar = 42;
}
void setup ()
{
handler ();
}
void loop () {}
However there is a problem if you try to pass your own defined class to a function, because of the automatic function prototype generation, which puts the prototypes before where the type is defined.
I just raised a bug report about that a few minutes ago:
http://code.google.com/p/arduino/issues/detail?id=973
On the bright side, if I may say without sounding pompous, most people who define a class in C++ would put it into its own .h files. That is really where class definitions belong. Then they can be shared between multiple .cpp files. You can do that under the Arduino IDE (making a new tab), it compiles correctly, and is easy to work with.
Whatever it is, it really aint C++ if you can't define classes.
Yep, you can define classes.