Is there a constraint that restricts my generic method to numeric types?

Question

Can anyone tell me if there is a way with generics to limit a generic type argument T to only:

• Int16
• Int32

Answer 1

I had a similar situation where I needed to handle numeric types and strings; seems a bit of a bizarre mix but there you go.

Again, like many people I looked at constraints and came up with a bunch of interfaces that it had to support. However, a) it wasn't 100% watertight and b), anyone new looking at this long list of constraints would be immediately very confused.

So, my approach was to put all my logic into a generic method with no constraints, but to make that generic method private. I then exposed it with public methods, one explicitly handling the type I wanted to handle - to my mind, the code is clean and explicit, e.g.

public static string DoSomething(this int input, ...) => DoSomethingHelper(input, ...);
public static string DoSomething(this decimal input, ...) => DoSomethingHelper(input, ...);
public static string DoSomething(this double input, ...) => DoSomethingHelper(input, ...);
public static string DoSomething(this string input, ...) => DoSomethingHelper(input, ...);

private static string DoSomethingHelper(this T input, ....)
{
    // complex logic
}