I was writing a generic
as the Constraint
, and the compiler spat a few errors that did not directly convey to me that
s cannot be used as generic constraints. And I learnt the following from my investigation:
This is an excerpt from the C# Language Specification.
Enums are value types and there is no way that you can specify the
System.ValueType as a constraint, as per the specification. But if you wish to specify a non-reference type as a [primary] constraint,
struct can be used.
private void Method<t> where T : struct
That does not guarantee that our generic method will not accept other value types, besides
enum, for which we do not support our functionality.
During the course of investigation, I was extremely surprised to know that the numeric types like
float, etc. in C# are
struct. It is not far from the fact that they are value types, but it was interesting to know that they are declared as:
public struct Int32 : IComparable, IFormattable, IConvertible,
Similar thing for other numeric types. Whereas an
enum [System.Enum], though a value type, is declared as an
abstract class that derives from
System.ValueTypes unlike the
float. The end result is that
enums are value types but I wonder about the way in which they are declared.
Anyway, the question still remains unresolved - why
enums cannot be used as constraints, and just the specification saying that
enums cannot be used as constraints is unsatisfactory.
I am not sure if there is any other way to resolve my situation. Question open to cyber space !!!
P.S. Refer to section 25.7 through for the specification on Generic Type Constraints.