Overlaying several CLR reference fields with each other in explicit struct?
- by thr
Edit: I'm well aware of that this works very well with value types, my specific question is about using this for reference types.
I've been tinkering around with structs in .NET/C#, and I just found out that you can do this:
using System;
using System.Runtime.InteropServices;
namespace ConsoleApplication1 {
class Foo { }
class Bar { }
[StructLayout(LayoutKind.Explicit)]
struct Overlaid {
[FieldOffset(0)] public object AsObject;
[FieldOffset(0)] public Foo AsFoo;
[FieldOffset(0)] public Bar AsBar;
}
class Program {
static void Main(string[] args) {
var overlaid = new Overlaid();
overlaid.AsObject = new Bar();
Console.WriteLine(overlaid.AsBar);
overlaid.AsObject = new Foo();
Console.WriteLine(overlaid.AsFoo);
Console.ReadLine();
}
}
}
Basically circumventing having to do dynamic casting during runtime by using a struct that has an explicit field layout and then accessing the object inside as it's correct type.
Now my question is: Can this lead to memory leaks somehow, or any other undefined behavior inside the CLR? Or is this a fully supported convention that is usable without any issues?
I'm aware that this is one of the darker corners of the CLR, and that this technique is only a viable option in very few specific cases.
