Restrict generic T to specific types

Question

I have the following method:

public static IResult Validate(this T value) {
} // Validate

How can I restrict T t

Answer 1

You can't restrict generics in that way, you can only choose a single class as a constraint. You must either make 5 overloads or find a interface all 5 of those things share and use that. Which option you choose will depend on what Validate doe.

Here is how you would do the overloads.

public static IResult Validate(this Int16 value) {
} // Validate

public static IResult Validate(this Int32 value) {
} // Validate

public static IResult Validate(this Int64 value) {
} // Validate

public static IResult Validate(this double value) {
} // Validate

public static IResult Validate(this String value) {
} // Validate

Here is by using a common interface, all of the members you list Implement IConvertible so you could restrict by that, however this will allow any IConvertible not just the 5 you listed.

public static IResult Validate(this T value) where IConvertible {
} // Validate