//Excerpt from visionary.C.

void visionary::decide(int *dx, int *dy) const
{
	static const unsigned radius = 3;   //of vision

	//Move one step away from a wabbit that could eat me.

	for (const_iterator it = begin(); it != end(); ++it) {
		const wabbit *const other = *it;

		if (other != static_cast<const wabbit *>(this) &&
			dist(this, other) <= radius &&
			other->hungry() > this->bitter()) {

			step(other, this, dx, dy);
			return;
		}
	}

	/*
	Arrive here if there were no enemies within the visual radius.
	Now see if there's any food I could eat within the visual radius.
	If so, take one step towards it.
	*/

	for (const_iterator it =
		do almost the same loop, ending with a step in the opposite
		direction: step(this, other, ...
	}

	//Arrive here if there were neither enemies nor food nearby:
	//lethargic (or random, if you wish) in the absence of stimulation.
	*dx = *dy = 0;
}