test.rs

struct Axes2D;

impl Axes2D
{
	fn new() -> Axes2D
	{
		Axes2D
	}
}

struct Axes3D;

impl Axes3D
{
	fn new() -> Axes2D
	{
		Axes2D
	}
}

enum AxesVariant
{
	Axes2DType(Axes2D),
	Axes3DType(Axes3D)
}

impl AxesVariant
{
	fn command(self) -> &'static str
	{
		match self
		{
			Axes2DType(_) => "plot",
			Axes3DType(_) => "splot",
		}
	}
}

struct Figure
{
	priv axes: ~[AxesVariant]
}

impl Figure
{
	fn new() -> Figure
	{
		Figure
		{
			axes: ~[]
		}
	}
	
	fn axes2d<'l>(&'l mut self) -> &'l mut Axes2D
	{
		self.axes.push(Axes2DType(Axes2D::new()));
		match self.axes[0]
		{
			Axes2DType(ref mut a) => a,
			_ => fail!()
		}
	}
}

fn main()
{

}