I want to declare a nested enum like:
\\pseudocode
public enum Animal
{
dog = 0,
cat = 1
}
private enum dog
{
bulldog = 0,
greyhound = 1,
husky = 3
}
private enum cat
{
persian = 0,
siamese = 1,
burmese = 2
}
Animal patient1 = Animal.dog.husky;
Can it be done?
Simply, no, it cannot.
I recommend that you define all of the values within the Animal enum. Is there any reason why you want this particular structure?
Switch to Java and it can be :)
enum Animal { enum Dog { BARK, WAG }; };
I don't think it works that way.
Enumerations are supposed to be a simple set of parallel values.
You may want to express that relationship with inheritance.
You can use this method to get what you want though
public static class Animal {
public enum Dog {
BullDog,
GreyHound,
Huskey
}
public enum Cat {
Tabby,
Bombbay
}
}
See these questions:
http://stackoverflow.com/questions/940002/getting-static-field-values-of-a-type-using-reflection
http://stackoverflow.com/questions/958606/storing-string-values-as-constants-in-the-same-manner-as-enum
The questions cover building a basic string enum, but I implement my answers using an ICustomEnum<T> interface that might help you in this situation.
Perhaps this would suffice?
class A
{
public const int Foo = 0;
public const int Bar = 1;
}
class B : A
{
public const int Baz = 2;
}
I would probably use a combination of enumerated bit fields and extension methods to achieve this. For example:
public enum Animal
{
None = 0x00000000,
AnimalTypeMask = 0xFFFF0000,
Dog = 0x00010000,
Cat = 0x00020000,
Alsation = Dog | 0x00000001,
Greyhound = Dog | 0x00000002,
Siamese = Cat | 0x00000001
}
public static class AnimalExtensions
{
public bool IsAKindOf(this Animal animal, Animal type)
{
return (((int)animal) & AnimalTypeMask) == (int)type);
}
}
Update
In .NET 4, you can use the Enum.HasFlag method rather than roll your own extension.
how do you use this function in code?
public bool IsAKindOf(this Animal animal, Animal type)