Hello Neil!

Replying to a message of Neil Heller to John Guillory:

 NH> 
 JG>>> -> typedef void * (*x) (void *)

 JG>>> -> What does this statement declare?

 JG>>> -> What is x?
 JG>>   I'm not an expert on C, but it appears like

 JG>> X is a pointer to a function that returns (I think a generic pointer)
 JG>> and takes on a generic pointer (void *).... In other words

Hmmm...

 NH> It seems to me that x is the return type from the function.  What's 
 NH> being returned is a pointer to that type.

 NH> I was wondering if the original statement is recursive?

Not at all.

typedef void* (*callback_t)(void *);
error_t do_stuff(callback_t function, void* data)
{
  error_t error = NO_ERROR;
  /* stuff, stuff, stuff */
  data = function(data);
  /* stuff, stuff, stuff */
  return error;
}

Now you can write any number of callback functions that match the
callback_t typedef's prototype, and use them in the do_stuff function.  The
function that you pass in must be a function that takes a pointer, and
returns a pointer.

Darin

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