C#8.0中的模式匹配

class Point
{
    public int X { get; }
    public int Y { get; }
    public Point(int                x, int     y) => (X, Y) = (x, y);
    public void Deconstruct(out int x, out int y) => (x, y) = (X, Y);
}

static string Display(object o)
{
    switch (o)
    {
        case Point p when p.X == 0 && p.Y == 0:
            return "origin";
        case Point p:
            return $"({p.X}, {p.Y})";
        default:
            return "unknown";
    }
}

static string Display(object o) => o switch
{
    Point p when p.X == 0 && p.Y == 0 => "origin",
    Point p                           => $"({p.X}, {p.Y})",
    _                                 => "unknown"
};

static string Display(object o) => o switch
{
    Point { X: 0, Y: 0 } => "origin",
    Point p              => $"({p.X}, {p.Y})",
    _                    => "unknown"
};

static string Display(object o) => o switch
{
    Point { X: 0, Y: 0 }         => "origin",
    Point { X: var x, Y: var y } => $"({x}, {y})",
    _                            => "unknown"
};

static string Display(object o) => o switch
{
    Point(0, 0)         => "origin",
    Point(var x, var y) => $"({x}, {y})",
    _                   => "unknown"
};

static string Display(Point o) => o switch
{
    (0, 0)         => "origin",
    (var x, var y) => $"({x}, {y})"
};

{ }  => o.ToString(),
null => "null"	

static State ChangeState(State current, Transition transition, bool hasKey) =>
    (current, transition, hasKey) switch
{
    (Opened, Close, _)     => Closed,
    (Closed, Open,  _)     => Opened,
    (Closed, Lock, true)   => Locked,
    (Locked, Unlock, true) => Closed,
    _ => throw new InvalidOperationException($"Invalid transition")
};