Reputation: 2094
First of all, I want to say that I'm new to C#, so this question may seem completely off track.
I have a set of enumerables called ShapeType:
Cube, Sphere, Rectangle, Ellipse
And a method to return a random value from the enumerables:
private static ShapeType GetRandomShape()
{
Array values = Enum.GetValues(typeof(ShapeType));
Random random = new Random();
ShapeType randomShape = (ShapeType)values.GetValue(random.Next(values.Length));
return randomShape;
}
Every enumerable has a corresponding concrete class. And the question I'm wondering about is if you can instantiate a class by using the random enumerable value randomShape, kind of like this:
private static Shape GetRandomShape()
{
Array values = Enum.GetValues(typeof(ShapeType));
Random random = new Random();
ShapeType randomShape = (ShapeType)values.GetValue(random.Next(values.Length));
Shape shape = new randomShape(); // *Here use the randomShape-variable as type*
return shape;
}
Is this possible or is it just wishful thinking?
Upvotes: 6
Views: 536
Reputation: 22008
Instead of
enum ShapeType { Cube, Sphere, Rectangle, Ellipse }
You can use something like
abstract class Figure
{
protected int id;
public static implicit operator int(Figure figure) => figure.id;
public static implicit operator Figure(int value) => Figures().First(figure => figure.id == value);
protected Figure(int id)
{
this.id = id;
}
public static Cube Cube { get; } = new Cube(1);
public static Sphere Sphere { get; } = new Sphere(2);
public static IEnumerable<Figure> Figures()
{
yield return Cube;
yield return Sphere;
}
public override string ToString() => this.GetType().ToString();
}
class Cube : Figure
{
public Cube(int id) : base(id) { }
}
class Sphere : Figure
{
public Sphere(int id) : base(id) { }
}
this will let you to do something like:
Console.WriteLine((object)(Figure)1); // Cube
Console.WriteLine((object)(Figure)2); // Sphere
I am using such approach in many places instead of enum
, which is often not sufficient (as it needs to hold extra information than just name and int
).
Upvotes: 0
Reputation: 31204
Create a Dictionary, with enumvalue as key, and type as value.
Dictionary<ShapeType, Type> dic = new Dictionary<ShapeType, Type>();
dic.Add(ShapeType.Cube, typeof(Cube));
// ...
private static Shape GetRandomShape()
{
Array values = Enum.GetValues(typeof(ShapeType));
Random random = new Random();
ShapeType randomShape = (ShapeType)values.GetValue(random.Next(values.Length));
Shape shape = Activator.CreateInstance(dic[randomShape]); // *Here use the randomShape-variable as type*
return shape;
}
Upvotes: 1
Reputation: 8878
You can use a dictionary to retrieve a factory function for every value of the enum:
static readonly Dictionary<ShapeType, Func<Shape>> _factoryLookup = new Dictionary<ShapeType, Func<Shape>>
{
[ShapeType.Cube] = () => new Cube(),
[ShapeType.Ellipse] = () => new Ellipse(),
[ShapeType.Rectangle] = () => new Rectangle(),
[ShapeType.Sphere] = () => new Sphere(),
};
static readonly Random random = new Random();
private static Shape GetRandomShape()
{
Array values = Enum.GetValues(typeof(ShapeType));
ShapeType randomShape = (ShapeType)values.GetValue(random.Next(values.Length));
Func<Shape> factory = _factoryLookup[randomShape];
Shape shape = factory();
return shape;
}
Upvotes: 3
Reputation: 5764
You need to use factory method pattern:
public class Shape {}
public class Cube : Shape {}
public class Sphere : Shape {}
public class Rectangle : Shape {}
public class Ellipse : Shape {}
public Shape randomShape(ShapeType shapeType)
{
switch(shapeType)
{
case ShapeType.Cube:
return new Cube();
...
}
}
Upvotes: 2